Method for transmitting and receiving signal in wireless communication system and apparatus therefor

ABSTRACT

The present invention relates to a method for receiving a downlink signal and an apparatus therefor. Specifically, the method for receiving a downlink signal comprises the steps of: receiving first time offset information and second time offset information from a base station, wherein the first time offset information and the second time offset information each indicate the time offset between the reception time of a specific signal and the reception time of a specific channel associated with the specific signal, and the first time offset information is set to have a length shorter than that of the second time offset information; and monitoring the specific signal at a time position determined on the basis of one of the first time offset information and the second time offset information, wherein the one offset information is determined on the basis of the capability of a user device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/KR2019/005642, filed on May 10, 2019, which claims the benefit ofKorean Application No. 10-2018-0057444, filed on May 18, 2018, andKorean Application No. 10-2018-0053973, filed on May 10, 2018. Thedisclosures of the prior applications are incorporated by reference intheir entirety.

TECHNICAL FIELD

The present disclosure relates to a wireless communication system, andmore specifically relates to a method of transmitting or receiving adownlink signal or channel and an apparatus therefor.

BACKGROUND

Mobile communication systems were developed to provide voice serviceswhile ensuring mobility of users. However, mobile communication systemshave been extended to data services as well as voice services, and moreadvanced communication systems are needed as the explosive increase intraffic now leads to resource shortages and users demand higher speedservices.

Requirements of the next generation mobile communication systems are tosupport accommodation of explosive data traffics, dramatic increases inthroughputs per user, accommodation of significantly increased number ofconnected devices, very low end-to-end latency, and high energyefficiency. To this end, various technologies such as Dual Connectivity,Massive Multiple Input Multiple Output (Massive MIMO), In-band FullDuplex, Non-Orthogonal Multiple Access (NOMA), support of Superwideband, and Device Networking are under research.

SUMMARY

An aspect of the present disclosure is to provide a method and apparatusfor efficiently transmitting and receiving a downlink signal or channel.

Particularly, an aspect of the present disclosure is to provide a methodand apparatus for efficiently transmitting and receiving a downlinksignal or channel by effectively configuring a relationship between aspecific signal or channel carrying information and a signal or channelto which the information is targeted.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present disclosure are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present disclosure could achieve will be more clearlyunderstood from the following detailed description.

In a first aspect of the present disclosure, provided herein is a methodof receiving a downlink signal by a user equipment, the methodcomprising: receiving first time offset information and second timeoffset information from a base station, each of the first time offsetinformation and the second time offset information indicating a timeoffset between a receiving time of a specific signal and a receivingtime of a specific channel related to the specific signal, the firsttime offset information being configured to have a shorter length thanthe second time offset information; and monitoring the specific signalat a time position determined based on one offset information of thefirst time offset information and the second time offset information,wherein the one offset information may be determined based on acapability of the user equipment.

In a second aspect of the present disclosure, provided herein is a userequipment for receiving a downlink signal in a wireless communicationsystem, the user equipment comprising: a transceiver; and a processoroperatively connected to the transceiver, wherein the processor isconfigured to: control the transceiver to receive first time offsetinformation and second time offset information from a base station, andmonitor the specific signal at a time position determined based on oneoffset information of the first time offset information and the secondtime offset information, wherein each of the first time offsetinformation and the second time offset information may indicate a timeoffset between a receiving time of a specific signal and a receivingtime of a specific channel related to the specific signal, and the firsttime offset information may be configured to have a shorter length thanthe second time offset information, and wherein the one offsetinformation may be determined based on a capability of the userequipment.

In a third aspect of the present disclosure, provided herein is anapparatus for a user equipment for receiving a downlink signal in awireless communication system, the apparatus comprising: a memoryincluding executable codes; and a processor operatively connected to thememory, wherein the processor is configured to execute the executablecodes to implement operations comprising: receiving first time offsetinformation and second time offset information from a base station, andmonitoring the specific signal at a time position determined based onone offset information of the first time offset information and thesecond time offset information, wherein each of the first time offsetinformation and the second time offset information may indicate a timeoffset between a receiving time of a specific signal and a receivingtime of a specific channel related to the specific signal, and the firsttime offset information may be configured to have a shorter length thanthe second time offset information, and wherein the one offsetinformation may be determined based on a capability of the userequipment.

Preferably, the first time offset information and the second time offsetinformation may be received through a system information block (SIB).

More preferably, the first time offset information and the second timeoffset information may be received through independent fields of theSIB.

Preferably, the first time offset information and the second time offsetinformation may be received through a radio resource control (RRC)signal.

More preferably, the first time offset information and the second timeoffset information may be received through independent fields of the RRCsignal.

Preferably, each of the first time offset information and the secondtime offset information may indicate a time offset between a receptionending time of the specific signal and a reception starting time of thespecific channel.

Preferably, each of the first time offset information and the secondtime offset information may indicate a time offset between a receptionstarting time of the specific signal and a reception starting time ofthe specific channel.

Preferably, the time position may be determined based on a pagingoccasion (PO) configured for the user equipment and the one time offsetinformation.

Preferably, the capability of the user equipment may be reported to thebase station.

Preferably, the method or the operations may further comprise monitoringthe specific channel based on detection of the specific signal.

Preferably, the specific signal may be a physical signal, and thespecific channel may be a physical control channel.

Preferably, the physical signal may be a wake up signal (WUS), and thephysical control channel may be a narrowband physical downlink controlchannel (NPDCCH) for paging.

According to the present disclosure, a downlink signal or channel may beefficiently transmitted or received.

Particularly according to the present disclosure, a downlink signal orchannel may be efficiently transmitted or received by effectivelyconfiguring a relationship between a specific signal or channel carryinginformation and a signal or channel to which the information istargeted.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved with the present disclosure are not limited to whathas been particularly described hereinabove and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure, illustrate embodiments of thedisclosure and together with the description serve to explain theprinciple of the disclosure.

FIG. 1 illustrates an example of the 3GPP LTE system architecture.

FIG. 2 illustrates an example of the 3GPP NR system architecture.

FIG. 3 illustrates a radio frame structure of frame structure type 1

FIG. 4 illustrates a radio frame structure of frame structure type 2.

FIG. 5 illustrates an example of a frame structure in NR.

FIG. 6 illustrates a resource grid for one DL slot.

FIG. 7 illustrates the structure of a downlink subframe.

FIG. 8 illustrates the structure of an uplink subframe.

FIG. 9 illustrates an example of a resource grid in NR.

FIG. 10 illustrates an example of a physical resource block in NR.

FIG. 11 illustrates a block diagram of a wireless communicationapparatus to which the methods proposed in the present disclosure areapplicable.

FIGS. 12A and 12B illustrate examples of narrowband operations andfrequency diversity.

FIG. 13 illustrates physical channels available in MTC and a generalsignal transmission method using the same.

FIGS. 14A and 14B illustrate an example of system informationtransmissions in MTC.

FIG. 15 illustrates an example of scheduling for each of MTC and legacyLTE.

FIGS. 16 and 17 illustrate examples of NB-IoT frame structures accordingto subcarrier spacing.

FIG. 18 illustrates an example of the resource grid for NB-IoT UL.

FIGS. 19A to 19C illustrate an examples of operation modes supported inthe NB-IoT system.

FIG. 20 illustrates an example of physical channels available in theNB-IoT and a general signal transmission method using the same.

FIG. 21 illustrates an example of the initial access procedure in theNB-IoT.

FIG. 22 illustrates an example of the random access procedure in theNB-IoT.

FIG. 23 illustrates an example of DRX mode in an idle state and/or aninactive state.

FIG. 24 illustrates an example of a DRX configuration and indicationprocedure for the NB-IoT UE.

FIG. 25 to FIG. 31 illustrate examples to which the methods according tothe present disclosure is applied.

FIG. 32 and FIG. 33 illustrate exemplary flowcharts of the methodsaccording to the present disclosure.

FIG. 34 illustrates an example of block diagrams of wirelesscommunication apparatuses to which the methods proposed in the presentdisclosure are applicable.

FIG. 35 illustrates exemplary 5G use scenarios.

DETAILED DESCRIPTION

In the following, downlink (DL) refers to communication from a basestation (BS) to a user equipment (UE), and uplink (UL) refers tocommunication from the UE to the BS. In the case of DL, a transmittermay be a part of the BS, and a receiver may be a part of the UE. In thecase of UL, a transmitter may be a part of the UE, and a receiver may bea part of the BS.

The technology described herein is applicable to various wireless accesssystems such as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier frequencydivision multiple access (SC-FDMA), etc. The CDMA may be implemented asradio technology such as universal terrestrial radio access (UTRA) orCDMA2000. The TDMA may be implemented as radio technology such as globalsystem for mobile communications (GSM), general packet radio service(GPRS), or enhanced data rates for GSM evolution (EDGE). The OFDMA maybe implemented as radio technology such as the Institute of Electricaland Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),IEEE 802-20, evolved UTRA (E-UTRA), etc. The UTRA is a part of auniversal mobile telecommunication system (UMTS). The 3rd generationpartnership project (3GPP) long term evolution (LTE) is a part of anevolved UMTS (E-UMTS) using the E-UTRA. LTE-advance (LTE-A) or LTE-A prois an evolved version of the 3GPP LTE. 3GPP new radio or new radioaccess technology (3GPP NR) is an evolved version of the 3GPP LTE,LTE-A, or LTE-A pro.

Although the present disclosure is described based on 3GPP communicationsystems (e.g., LTE-A, NR, etc.) for clarity of description, the spiritof the present disclosure is not limited thereto. The LTE refers to thetechnology beyond 3GPP technical specification (TS) 36.xxx Release 8. Inparticular, the LTE technology beyond 3GPP TS 36.xxx Release 10 isreferred to as the LTE-A, and the LTE technology beyond 3GPP TS 36.xxxRelease 13 is referred to as the LTE-A pro. The 3GPP NR refers to thetechnology beyond 3GPP TS 38.xxx Release 15. The LTE/NR may be called‘3GPP system’. Herein, “xxx” refers to a standard specification number.The LTE/NR may be commonly referred to as ‘3GPP system’. Details of thebackground, terminology, abbreviations, etc. used herein may be found indocuments published before the present disclosure. For example, thefollowing documents may be referenced.

3GPP LTE

-   -   36.211: Physical channels and modulation    -   36.212: Multiplexing and channel coding    -   36.213: Physical layer procedures    -   36.300: Overall description    -   36.331: Radio Resource Control (RRC)

3GPP NR

-   -   38.211: Physical channels and modulation    -   38.212: Multiplexing and channel coding    -   38.213: Physical layer procedures for control    -   38.214: Physical layer procedures for data    -   38.300: NR and NG-RAN Overall Description    -   36.331: Radio Resource Control (RRC) protocol specification

A. System Architecture

FIG. 1 illustrates an example of the 3GPP LTE system architecture.

A wireless communication system may be referred to as an evolved-UMTSterrestrial radio access network (E-UTRAN) or a long term evolution(LTE)/LTE-A system. Referring to FIG. 1, the E-UTRAN includes at leastone BS 20 that provides control and user planes to a UE 10. The UE 10may be fixed or mobile. The UE 10 may be referred to as anotherterminology such as ‘mobile station (MS)’, ‘user terminal (UT)’,‘subscriber station (SS)’, ‘mobile terminal (MT)’, or ‘wireless device’.In general, the BS 20 may be a fixed station that communicates with theUE 10. The BS 20 may be referred to as another terminology such as‘evolved Node-B (eNB)’, ‘general Node-B (gNB)’, ‘base transceiver system(BTS)’, or ‘access point (AP)’. The BSs 20 may be interconnected throughan X2 interface. The BS 20 may be connected to an evolved packet core(EPC) through an S1 interface. More particularly, the BS 20 may beconnected to a mobility management entity (MME) through S1-MME and to aserving gateway (S-GW) through S1-U. The EPC includes the MME, the S-GW,and a packet data network-gateway (P-GW). Radio interface protocollayers between the UE and network may be classified into Layer 1 (L1),Layer 2 (L2), and Layer 3 (L3) based on three lower layers of the opensystem interconnection (OSI) model well known in communication systems.A physical (PHY) layer, which belongs to L1, provides an informationtransfer service over a physical channel. A radio resource control (RRC)layer, which belongs to L3, controls radio resources between the UE andnetwork. To this end, the BS and UE may exchange an RRC message throughthe RRC layer.

FIG. 2 illustrates an example of the 3GPP NR system architecture.

Referring to FIG. 2, a NG-RAN includes gNBs, each of which provides aNG-RA user plane (e.g., new AS sublayer/PDCP/RLC/MAC/PHY) and a controlplane (RRC) protocol terminal to a UE. The gNBs are interconnectedthrough an Xn interface. The gNB is connected to an NGC through a NGinterface. More particularly, the gNB is connected to an access andmobility management function through an N2 interface and to a user planefunction (UPF) through an N3 interface.

B. Frame Structure

Hereinafter, an LTE frame structure will be described.

In the LTE standards, the sizes of various fields in the time domain areexpressed in a time unit (Ts=1/(15000×2048) seconds) unless specifiedotherwise. DL and UL transmissions are organized in radio frames, eachof which has a duration of 10 ms (Tf=307200×Ts=10 ms). Two radio framestructures are supported.

-   -   Type 1 is applicable to frequency division duplex (FDD).    -   Type 2 is applicable to time division duplex (TDD).

(1) Frame Structure Type 1

Frame structure type 1 is applicable to both full-duplex FDD andhalf-duplex FDD. Each radio frame has a duration ofT_(f)=307200·T_(s)=10 ms and is composed of 20 slots, each of which hasa length of T_(slot)=15360·T_(s)=0.5 ms. The 20 slots are indexed from 0to 19. A subframe is composed of two consecutive slots. That is,subframe i is composed of slot 2 i and slot (2 i+1). In the FDD, 10subframes may be used for DL transmission, and 10 subframes may beavailable for UL transmissions at every interval of 10 ms. DL and ULtransmissions are separated in the frequency domain. However, the UE maynot perform transmission and reception simultaneously in the half-duplexFDD system.

FIG. 3 illustrates a radio frame structure of frame structure type 1.

Referring to FIG. 3, the radio frame includes 10 subframes. Eachsubframe includes two slots in the time domain. The time to transmit onesubframe is defined as a transmission time interval (TTI). For example,one subframe may have a length of 1 ms, and one slot may have a lengthof 0.5 ms. One slot may include a plurality of orthogonal frequencydivision multiplexing (OFDM) symbols in the time domain. Since the 3GPPLTE system uses OFDMA in DL, the OFDM symbol may represent one symbolperiod. The OFDM symbol may be referred to as an SC-FDMA symbol or asymbol period. A resource block (RB) is a resource allocation unit andincludes a plurality of consecutive subcarriers in one slot. This radioframe structure is merely exemplary. Therefore, the number of subframesin a radio frame, the number of slots in a subframe, or the number ofOFDM symbols in a slot may be changed in various ways.

(2) Frame Structure Type 2

Frame structure type 2 is applicable to TDD. Each radio frame has alength of T_(f)=307200×T_(s)=10 ms and includes two half-frames, each ofwhich has a length of 15360·T_(s)=0.5 ms. Each half-frame includes fivesubframes, each of which has a length of 30720·T_(s)=1 ms SupportedUL-DL configurations are defined in the standards. In each subframe of aradio frame, “D” denotes a subframe reserved for DL transmission, “U”denotes a subframe reserved for UL transmission, and “S” denotes aspecial subframe including the following three fields: downlink pilottime slot (DwPTS), guard period (GP), and uplink pilot time slot(UpPTS). The DwPTS may be referred to as a DL period, and the UpPTS maybe referred to as a UL period. The lengths of the DwPTS and UpPTS dependon the total length of the DwPTS, GP, and UpPTS, which is equal to30720·T_(s)=1 ms Subframe i is composed of two slots, slot 2 i and slot(2 i+1), each of which has a length of T_(slot)=15360·T_(s)=0.5 ms.

FIG. 4 illustrates a radio frame structure of frame structure type 2.

FIG. 4 shows that a UL-DL configuration supports DL-to-UL switch-pointperiodicities of 5 ms and 10 ms. In the case of the 5-ms DL-to-ULswitch-point periodicity, the special subframe exists across twohalf-frames. In the case of the 10-ms DL-to-UL switch-point periodicity,the special subframe exists only in the first half-frame. The DwPTS andsubframe 0 and 5 are always reserved for DL transmission, and the UpPTSand a subframe next to the special subframe are always reserved for ULtransmission.

Next, a description will be given of a frame structure of NR.

FIG. 5 illustrates an example of a frame structure in NR.

The NR system may support various numerologies. The numerology may bedefined by subcarrier spacing and cyclic prefix (CP) overhead. Multiplesubcarrier spacing may be derived by scaling basic subcarrier spacing byan integer N (or μ). In addition, even though very low subcarrierspacing is assumed not to be used at a very high subcarrier frequency, anumerology to be used may be selected independently from frequencybands. In the NR system, various frame structures may be supported basedon multiple numerologies.

Hereinafter, an OFDM numerology and a frame structure, which may beconsidered in the NR system, will be described. Table 1 shows multipleOFDM numerologies supported in the NR system.

TABLE 1 μ Δf = 2^(μ) · 15 [kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal

Regarding a frame structure in the NR system, the sizes of variousfields in the time domain are expressed in multiples of a time unit,T_(s)=1/(Δf_(max)·N_(f)). In this case, Δf_(max)=480·10³ and N_(f)=4096.Downlink and uplink transmissions are configured in a radio frame havinga duration of T_(f)=(Δf_(max)N_(f)/100)·T_(s)=10 ms. The radio frame iscomposed of 10 subframes, each having a duration ofT_(sf)=(Δf_(max)N_(f)/1000)·T_(s)=1 ms. In this case, there may be a setof uplink frames and a set of downlink frames. Transmission of an uplinkframe with frame number i from a UE needs to be performed earlier byT_(TA)=N_(TA)T_(s) than the start of a corresponding downlink frame ofthe UE. Regarding the numerology μ, slots are numbered in a subframe inthe following ascending order: n_(s) ^(μ)ϵ{0, . . . , N_(subframe)^(slots,μ)−1} and numbered in a frame in the following ascending order:n_(s,f) ^(μ)ϵ{0, . . . , N_(frame) ^(slots,μ)−1}. One slot is composedof N_(symb) ^(μ) consecutive OFDM symbols, and N_(symb) ^(μ) isdetermined by the current numerology and slot configuration. The startsof n_(s) ^(μ) slots in a subframe are temporally aligned with those ofn_(s) ^(μ)N_(symb) ^(μ) OFDM symbols in the same subframe. Some UEs maynot perform transmission and reception at the same time, and this meansthat some OFDM symbols in a downlink slot or an uplink slot areunavailable. Table 2 shows the number of OFDM symbols per slot (N_(symb)^(slot)) the number of slots per radio frame (N_(slot) ^(frame,μ)), andthe number of slots per subframe (N_(slot) ^(subframe,μ)) in the case ofa normal CP, and Table 3 shows the number of OFDM symbols per slot, thenumber of slots per radio frame, and the number of slots per subframe inthe case of an extended CP.

TABLE 2 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

TABLE 3 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)2 12 40 4

FIG. 3 shows an example of μ=2, i.e., 60 kHz subcarrier spacing (SCS).Referring to Table 2, one subframe may include four slots. FIG. 5 showsslots in a subframe (subframe={1, 2, 4}). In this case, the number ofslots included in the subframe may be defined as shown in Table 2 above.

In addition, a mini-slot may be composed of 2, 4, or 7 symbols.Alternatively, the number of symbols included in the mini-slot may vary.

C. Physical Resource

FIG. 6 illustrates a resource grid for one DL slot.

Referring to FIG. 6, a downlink slot includes a plurality of OFDMsymbols in the time domain. One downlink slot includes 7 OFDM symbols inthe time domain, and a resource block (RB) for example includes 12subcarriers in the frequency domain. However, the present disclosure isnot limited thereto. Each element of the resource grid is referred to asa resource element (RE). One RB includes 12×7 REs. The number of RBs inthe DL slot depends on a downlink transmission bandwidth. An uplink slotmay have the same structure as the downlink slot.

FIG. 7 illustrates the structure of a downlink subframe.

Referring to FIG. 7, up to three OFDM symbols at the start of the firstslot in a downlink subframe are used as a control region to which acontrol channel is allocated. The remaining OFDM symbols are used as adata region to which a physical downlink shared channel (PDSCH) isallocated. Downlink control channels used in the 3GPP LTE system includea physical control format indicator channel (PCFICH), a physicaldownlink control channel (PDCCH), a physical hybrid ARQ indicatorchannel (PHICH), etc. The PCFICH is transmitted in the first OFDM symbolin a subframe and carries information for the number of OFDM symbolsused for transmitting a control channel. The PHICH carries a hybridautomatic repeat request (HARD) acknowledgement/negative-acknowledgementor not-acknowledgement (ACK/NACK) signal in response to uplinktransmission. Control information transmitted on the PDCCH is referredto as downlink control information (DCI). The DCI contains uplink ordownlink scheduling information or an uplink transmission (Tx) powercontrol command for a random UE group. The PDCCH carries information forresource allocation for a downlink shared channel (DL-SCH), informationfor resource allocation for a uplink shared channel, paging informationfor a paging channel (PCH), and a DL-SCH voice over Internet protocol(VoIP) corresponding to resource allocation for a higher layer controlmessage such as a random access response transmitted on the PDSCH, a setof Tx power control commands for individual UEs in a random UE group, aTx power control command, activation of the Tx power control command,etc. Multiple PDCCHs may be transmitted in the control region, and theUE may monitor the multiple PDCCHs. The PDCCH may be transmitted on onecontrol channel element (CCE) or aggregation of multiple consecutiveCCEs. The CCE is a logical allocation unit used to provide the PDCCHwith a coding rate based on the state of a radio channel. The CCEcorresponds to a plurality of resource element groups (REGs). A PDCCHformat and the number of available PDCCH bits are determined based on arelationship between the number of CCEs and the coding rate provided bythe CCE. The base station determines the PDCCH format depending on DCIto be transmitted to the UE and adds a cyclic redundancy check (CRC) tocontrol information. The CRC is masked with a unique identifier (e.g.,radio network temporary identifier (RNTI)) according to the owner orusage of the PDCCH. If the PDCCH is for a specific UE, the CRC may bemasked with a unique UE identifier (e.g., cell-RNTI). If the PDCCH isfor a paging message, the CRC may be masked with a paging indicationidentifier (e.g., paging-RNTI (P-RNTI)). If the PDCCH is for systeminformation (more specifically, for a system information block (SIB)),the CRC may be masked with a system information identifier and a systeminformation RNTI (SI-RNTI). Further, the CRC may be masked with a randomaccess-RNTI (RA-RNTI) to indicate a random access response in responseto transmission of a random access preamble of the UE.

FIG. 8 illustrates the structure of an uplink subframe.

Referring to FIG. 8, an uplink subframe may be divided into a controlregion and a data region in the frequency domain. A physical uplinkcontrol channel (PUCCH) for carrying uplink control information may beallocated to the control region, and a physical uplink shared channel(PUSCH) for carrying user data may be allocated to the data region. TheUE may not transmit the PUCCH and the PUSCH at the same time to maintainsingle-carrier characteristics. The PUCCH for the UE is allocated to anRB pair in a subframe. The RBs included in the RB pair occupy differentsubcarriers in two slots. In other words, the RB pair allocated for thePUCCH may be frequency-hopped at a slot boundary.

As physical resources in the NR system, an antenna port, a resourcegrid, a resource element, a resource block, a carrier part, etc. may beconsidered. Hereinafter, the above physical resources considered in theNR system will be described in detail. First, an antenna port may bedefined such that a channel carrying a symbol on the antenna port isinferred from a channel carrying another symbol on the same antennaport. When the large-scale properties of a channel carrying a symbol onan antenna port are inferred from a channel carrying a symbol on anotherantenna port, the two antenna ports may be said to be in quasico-located or quasi co-location (QC/QCL) relationship. The large-scaleproperties may include at least one of delay spread, Doppler spread,frequency shift, average received power, and received timing.

FIG. 9 illustrates an example of a resource grid in NR.

Referring to the resource grid of FIG. 9, there are N_(RB) ^(μ)N_(sc)^(RB) subcarriers in the frequency domain, and there are 14·2μ OFDMsymbols in one subframe. However, the resource grid is merely exemplaryand the present disclosure is not limited thereto. In the NR system, atransmitted signal is described by one or more resource grids, eachincluding N_(RB) ^(μ)N_(sc) ^(RB) subcarriers, and 2^(μ)N_(symb) ^((μ))OFDM symbols. In this case, N_(RB) ^(μ)≤N_(RB) ^(max,μ). N_(RB) ^(max,μ)denotes the maximum transmission bandwidth and may change not onlybetween numerologies but also between uplink and downlink. As shown inFIG. 9, one resource grid may be configured for each numerology μ andantenna port p. Each element of the resource grid for the numerology μand antenna port p is referred to as a resource element, and it isuniquely identified by an index pair (k,l), where k is an index in thefrequency domain (k=0, . . . , N_(RB) ^(μ)N_(sc) ^(RB)−1) and l denotesthe location of a symbol in the subframe (l=0, . . . , 2^(μ)N_(symb)^((μ))−1). The resource element (k,l) for the numerology μ and antennaport p corresponds to a complex value a_(k,j) ^((p,μ)). When there is norisk of confusion or when a specific antenna port or numerology is notspecified, the indexes p and μ may be dropped, and as a result, thecomplex value may be a_(k,j) ^((p)) or a_(k,j). In addition, a resourceblock (RB) is defined as N_(sc) ^(RB)=12 consecutive subcarriers in thefrequency domain.

Point A serves as a common reference point for resource block grids andmay be obtained as follows.

-   -   OffsetToPointA for primary cell (PCell) downlink represents a        frequency offset between point A and the lowest subcarrier of        the lowest resource block in an SS/PBCH block used by the UE for        initial cell selection. OffsetToPointA is expressed in the unit        of resource block on the assumption of 15 kHz SCS for frequency        range 1 (FR1) and 60 kHz SCS for frequency range 2 (FR2).    -   AbsoluteFrequencyPointA represents the frequency location of        point A expressed as in absolute radio-frequency channel number        (ARFCN).

Common resource blocks are numbered from 0 upwards in the frequencydomain for SCS configuration μ.

The center of subcarrier 0 of common resource block 0 for the SCSconfiguration μ is equivalent to point A.

The relation between a common RB number n_(CRB) ^(μ) in the frequencydomain and a resource element (k,l) for the SCS configuration μ isdetermined as shown in Equation 1.

$\begin{matrix}{n_{CRB}^{\mu} = \left\lfloor \frac{k}{N_{sc}^{RB}} \right\rfloor} & \left. {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation 1, k is defined relative to point A such that k=0corresponds to a subcarrier centered on point A.

Physical resource blocks are defined within a bandwidth part (BWP) andnumbered from 0 to N_(BWP,i) ^(size)−1, where i denotes the number ofthe BWP.

The relationship between a physical resource block n_(PRB) and a commonresource block n_(CRB) in BWP i is given by Equation 2.n _(CRB) =n _(PRB) +N _(BWP,i) ^(start)  Equation 2

In Equation 2, N_(BWP,i) ^(start) is a common resource block where theBWP starts relative to common resource block 0.

FIG. 10 illustrates an example of a physical resource block in NR.

D. Wireless Communication Devices

FIG. 11 illustrates a block diagram of a wireless communicationapparatus to which the methods proposed in the present disclosure areapplicable.

Referring to FIG. 11, a wireless communication system includes a basestation 1110 and multiple UEs 1120 located within coverage of the basestation 1110. The base station 1110 and the UE may be referred to as atransmitter and a receiver, respectively, and vice versa. The basestation 1110 includes a processor 1111, a memory 1114, at least onetransmission/reception (Tx/Rx) radio frequency (RF) module (or RFtransceiver) 1115, a Tx processor 1112, an Rx processor 1113, and anantenna 1116. The UE 1120 includes a processor 1121, a memory 1124, atleast one Tx/Rx RF module (or RF transceiver) 1125, a Tx processor 1122,an Rx processor 1123, and an antenna 1126. The processors are configuredto implement the above-described functions, processes and/or methods.Specifically, the processor 1111 provides a higher layer packet from acore network for downlink (DL) transmission (communication from the basestation to the UE). The processor implements the functionality of layer2 (L2). In downlink (DL), the processor provides the UE 1120 withmultiplexing between logical and transmission channels and radioresource allocation. That is, the processor is in charge of signaling tothe UE. The Tx processor 1112 implements various signal processingfunctions of layer 1 (L1) (i.e., physical layers). The signal processingfunctions include facilitating the UE to perform forward errorcorrection (FEC) and performing coding and interleaving. Coded andmodulated symbols may be divided into parallel streams. Each stream maybe mapped to an OFDM subcarrier, multiplexed with a reference signal(RS) in the time and/or frequency domain, and then combined togetherusing an inverse fast Fourier transform (IFFT) to create a physicalchannel carrying a time domain OFDMA symbol stream. The OFDM stream isspatially precoded to produce multiple spatial streams. Each spatialstream may be provided to a different antenna 1116 through the Tx/Rxmodule (or transceiver) 1115. Each Tx/Rx module may modulate an RFcarrier with each spatial stream for transmission. At the UE, each Tx/Rxmodule (or transceiver) 1125 receives a signal through each antenna 1126thereof. Each Tx/Rx module recovers information modulated on the RFcarrier and provides the information to the RX processor 1123. The Rxprocessor implements various signal processing functions of layer 1. TheRx processor may perform spatial processing on the information torecover any spatial streams toward the UE. If multiple spatial streamsare destined for the UE, the multiple spatial streams may be combined bymultiple Rx processors into a single OFDMA symbol stream. The RXprocessor converts the OFDMA symbol stream from the time domain to thefrequency domain using a fast Fourier transform (FFT). Afrequency-domain signal includes a separate OFDMA symbol stream for eachsubcarrier of an OFDM signal. The symbols and the reference signal oneach subcarrier are recovered and demodulated by determining the mostprobable signal constellation points transmitted by the base station.Such soft decisions may be based on channel estimation values. The softdecisions are decoded and deinterleaved to recover data and controlsignals originally transmitted by the base station over the physicalchannel. The corresponding data and control signals are provided to theprocessor 1121.

Uplink (UL) transmission (communication from the UE to the base station)is processed by the base station 1110 in a similar way to that describedin regard to the receiver functions of the UE 1120. Each Tx/Rx module(or transceiver) 1125 receives a signal through each antenna 1126. EachTx/Rx module provides an RF carrier and information to the Rx processor1123. The processor 1121 may be connected to the memory 1124 storingprogram codes and data. The memory may be referred to as acomputer-readable medium.

E. Machine Type Communication (MTC)

The Machine Type Communication (MTC) refers to communication technologyadopted by 3^(rd) Generation Partnership Project (3GPP) to meet Internetof Things (IoT) service requirements. Since the MTC does not requirehigh throughput, it may be used as an application for machine-to-machine(M2M) and Internet of Things (IoT).

The MTC may be implemented to satisfy the following requirements: (i)low cost and low complexity; (ii) enhanced coverage; and (iii) low powerconsumption.

The MTC was introduced in 3GPP release 10. Hereinafter, the MTC featuresadded in each 3GPP release will be described.

The MTC load control was introduced in 3GPP releases 10 and 11.

The load control method prevents IoT (or M2M) devices from creating aheavy load on the base station suddenly.

Specifically, according to release 10, when a load occurs, the basestation may disconnect connections with IoT devices to control the load.According to release 11, the base station may prevent the UE fromattempting to establish a connection by informing the UE that accesswill become available through broadcasting such as SIB14.

In release 12, the features of low-cost MTC were added, and to this end,UE category 0 was newly defined. The UE category indicates the amount ofdata that the UE is capable of processing using a communication modem.

Specifically, a UE that belongs to UE category 0 may use a reduced peakdata rate, a half-duplex operation with relaxed RF requirements, and asingle reception antenna, thereby reducing the baseband and RFcomplexity of the UE.

In Release 13, enhanced MTC (eMTC) was introduced. In the eMTC, the UEoperates in a bandwidth of 1.08 MHz, which is the minimum frequencybandwidth supported by legacy LTE, thereby further reducing the cost andpower consumption.

Although the following description relates to the eMTC, the descriptionis equally applicable to the MTC, 5G (or NR) MTC, etc. For convenienceof description, all types of MTC is commonly referred to as ‘MTC’.

In the following description, the MTC may be referred to as anotherterminology such as eMTC′, ‘bandwidth reduced low complexity/coverageenhanced (BL/CE)’, ‘non-BL UE (in enhanced coverage)’, ‘NR MTC’, or‘enhanced BL/CE’. Further, the term “MTC” may be replaced with a termdefined in the future 3GPP standards.

1) General Features of MTC

(1) The MTC operates only in a specific system bandwidth (or channelbandwidth).

The specific system bandwidth may use 6 RBs of the legacy LTE as shownin Table 4 below and defined by considering the frequency range andsubcarrier spacing (SCS) shown in Tables 5 to 7. The specific systembandwidth may be referred to as narrowband (NB). Here, the legacy LTEmay encompass the contents described in the 3GPP standards expect theMTC. In the NR, the MTC may use RBs corresponding the smallest systembandwidth in Tables 6 and 7 as in the legacy LTE. Alternatively, the MTCmay operate in at least one BWP or in a specific band of a BWP.

TABLE 4 Channel bandwidth BWChannel [MHz] 1.4 3 5 10 15 20 Transmission6 15 25 50 75 100 bandwidth configuration N_(RB)

Table 5 shows the frequency ranges (FRs) defined for the NR.

TABLE 5 Frequency range designation Corresponding frequency range FR1 450 MHz-6000 MHz FR2 24250 MHz-52600 MHz

Table 6 shows the maximum transmission bandwidth configuration (NRB) forthe channel bandwidth and SCS in NR FR1.

TABLE 6 5 10 15 20 25 30 40 50 60 80 90 100 SCS MHz MHz MHz MHz MHz MHzMHz MHz MHz MHz MHz MHz (kHz) NRB NRB NRB NRB NRB NRB NRB NRB NRB NRBNRB NRB 15 25 52 79 106 133 160 216 270 N/A N/A N/A N/A 30 11 24 38 5165 78 106 133 162 217 245 273 60 N/A 11 18 24 31 38 51 65 79 107 121 135

Table 7 shows the maximum transmission bandwidth configuration (NRB) forthe channel bandwidth and SCS in NR FR2.

TABLE 7 50 MHz 100 MHz 200 MHz 400 MHz SCS (kHz) NRB NRB NRB NRB 60 66132 264 N.A 120 32 66 132 264

Hereinafter, the MTC narrowband (NB) will be described in detail.

The MTC follows narrowband operation to transmit and receive physicalchannels and signals, and the maximum channel bandwidth is reduced to1.08 MHz or 6 (LTE) RBs.

The narrowband may be used as a reference unit for allocating resourcesto some downlink and uplink channels, and the physical location of eachnarrowband in the frequency domain may vary depending on the systembandwidth.

The 1.08 MHz bandwidth for the MTC is defined to allow an MTC UE tofollow the same cell search and random access procedures as those of thelegacy UE.

The MTC may be supported by a cell with a much larger bandwidth (e.g.,10 MHz), but the physical channels and signals transmitted/received inthe MTC are always limited to 1.08 MHz.

The larger bandwidth may be supported by the legacy LTE system, NRsystem, 5G system, etc.

The narrowband is defined as 6 non-overlapping consecutive physical RBsin the frequency domain.

If N_(NB) ^(UL)≥4, a wideband is defined as four non-overlappingnarrowbands in the frequency domain. If N_(NB) ^(UL)<4, N_(WB) ^(UL)=1and a single wideband is composed of N_(NB) ^(UL) non-overlappingnarrowband(s).

For example, in the case of a 10 MHz channel, 8 non-overlappingnarrowbands are defined.

FIGS. 12A and 12B illustrate examples of narrowband operations andfrequency diversity.

Specifically, FIG. 12A illustrates an example of the narrowbandoperation, and FIG. 12B illustrates an example of repetitions with RFretuning.

Hereinafter, frequency diversity by RF retuning will be described withreference to FIG. 12B.

The MTC supports limited frequency, spatial, and time diversity due tothe narrowband RF, single antenna, and limited mobility. To reduce theeffects of fading and outages, frequency hopping is supported betweendifferent narrowbands by the RF retuning.

The frequency hopping is applied to different uplink and downlinkphysical channels when repetition is enabled.

For example, if 32 subframes are used for PDSCH transmission, the first16 subframes may be transmitted on the first narrowband. In this case,the RF front-end is retuned to another narrowband, and the remaining 16subframes are transmitted on the second narrowband.

The MTC narrowband may be configured by system information or DCI.

(2) The MTC operates in half-duplex mode and uses limited (or reduced)maximum transmission power.

(3) The MTC does not use a channel (defined in the legacy LTE or NR)that should be distributed over the full system bandwidth of the legacyLTE or NR.

For example, the MTC does not use the following legacy LTE channels:PCFICH, PHICH, and PDCCH.

Thus, a new control channel, an MTC PDCCH (MPDCCH), is defined for theMTC since the above channels are not monitored.

The MPDCCH may occupy a maximum of 6 RBs in the frequency domain and onesubframe in the time domain.

The MPDCCH is similar to an evolved PDCCH (EPDCCH) and supports a commonsearch space for paging and random access.

In other words, the concept of the MPDCCH is similar to that of theEPDCCH used in the legacy LTE.

(4) The MTC uses newly defined DCI formats. For example, DCI formats6-0A, 6-0B, 6-1A, 6-1B, 6-2, etc. may be used.

In the MTC, a physical broadcast channel (PBCH), physical random accesschannel (PRACH), MPDCCH, PDSCH, PUCCH, and PUSCH may be repeatedlytransmitted. The MTC repeated transmission enables decoding of an MTCchannel in a poor environment such as a basement, that is, when thesignal quality or power is low, thereby increasing the radius of a cellor supporting the signal propagation effect. The MTC may support alimited number of transmission modes (TMs), which are capable ofoperating on a single layer (or single antenna), or support a channel orreference signal (RS), which are capable of operating on a single layer.For example, the MTC may operate in TM 1, 2, 6, or 9.

(6) In the MTC, HARQ retransmission is adaptive and asynchronous andperformed based on a new scheduling assignment received on the MPDCCH.

(7) In the MTC, PDSCH scheduling (DCI) and PDSCH transmission occur indifferent subframes (cross-subframe scheduling).

(8) All resource allocation information (e.g., a subframe, a transportblock size (TBS), a subband index, etc.) for SIB1 decoding is determinedby a master information block (MIB) parameter (in the MTC, no controlchannel is used for the SIB1 decoding).

(9) All resource allocation information (e.g., a subframe, a TBS, asubband index, etc.) for SIB2 decoding is determined by several SIB1parameters (in the MTC, no control channel is used for the SIB2decoding).

(10) The MTC supports an extended discontinuous reception (DRX) cycle.

(11) The MTC may use the same primary synchronization signal/secondarysynchronization signal/common reference signal (PSS/SSS/CRS) as thatused in the legacy LTE or NR. In the NR, the PSS/SSS is transmitted inthe unit of SS block (or SS/PBCH block or SSB), and a tracking RS (TRS)may be used for the same purpose as the CRS. That is, the TRS is acell-specific RS and may be used for frequency/time tracking.

2) MTC Operation Mode and Level

Hereinafter, MTC operation modes and levels will be described. Toenhance coverage, the MTC may be divided into two operation modes (firstand second modes) and four different levels as shown in Table 8 below.

The MTC operation mode may be referred to CE mode. The first and secondmodes may be referred to CE mode A and CE mode B, respectively.

TABLE 8 Mode Level Description Mode A Level 1 No repetition for PRACHLevel 2 Small Number of Repetition for PRACH Mode B Level 3 MediumNumber of Repetition for PRACH Level 4 Large Number of Repetition forPRACH

The first mode is defined for small coverage where full mobility andchannel state information (CSI) feedback are supported. In the firstmode, the number of repetitions is zero or small. The operation in thefirst mode may have the same operation coverage as that of UEcategory 1. The second mode is defined for a UE with a very poorcoverage condition where CSI feedback and limited mobility aresupported. In the second mode, the number of times that transmission isrepeated is large. The second mode provides up to 15 dB coverageenhancement with reference to the coverage of UE category 1. Each levelof the MTC is defined differently in RACH and paging procedures.

Hereinafter, a description will be given of how to determine the MTCoperation mode and level.

The MTC operation mode is determined by the base station, and each levelis determined by the MTC UE. Specifically, the base station transmitsRRC signaling including information for the MTC operation mode to theUE. The RRC signaling may include an RRC connection setup message, anRRC connection reconfiguration message, or an RRC connectionreestablishment message. Here, the term “message” may refer to aninformation element (IE).

The MTC UE determines a level within the operation mode and transmitsthe determined level to the base station. Specifically, the MTC UEdetermines the level within the operation mode based on measured channelquality (e.g., RSRP, RSRQ, SINR, etc.) and informs the base station ofthe determined level using a PRACH resource (e.g., frequency, time,preamble, etc.).

3) MTC Guard Period

As described above, the MTC operates in the narrowband. The location ofthe narrowband may vary in each specific time unit (e.g., subframe orslot). The MTC UE tunes to a different frequency in every time unit.Thus, all frequency retuning may require a certain period of time. Inother words, the guard period is required for transition from one timeunit to the next time unit, and no transmission and reception occursduring the corresponding period.

The guard period varies depending on whether the current link isdownlink or uplink and also varies depending on the state thereof. Anuplink guard period (i.e., guard period defined for uplink) variesdepending on the characteristics of data carried by a first time unit(time unit N) and a second time unit (time unit N+1). In the case of adownlink guard period, the following conditions need to be satisfied:(1) a first downlink narrowband center frequency is different from asecond narrowband center frequency; and (2) in TDD, a first uplinknarrowband center frequency is different from a second downlink centerfrequency.

The MTC guard period defined in the legacy LTE will be described. Aguard period consisting of at most N_(symb) ^(retune) SC-FDMA symbols iscreated for Tx-Tx frequency retuning between two consecutive subframes.When the higher layer parameter ce-RetuningSymbols is configured,N_(symb) ^(retune) is equal to ce-RetuningSymbols. Otherwise, N_(symb)^(retune) is 2. For an MTC UE configured with the higher layer parametersrs-UpPtsAdd, a guard period consisting of SC-FDMA symbols is createdfor Tx-Tx frequency retuning between a first special subframe and asecond uplink subframe for frame structure type 2.

FIG. 13 illustrates physical channels available in MTC and a generalsignal transmission method using the same.

When an MTC UE is powered on or enters a new cell, the MTC UE performsinitial cell search in step S1301. The initial cell search involvesacquisition of synchronization with a base station. Specifically, theMTC UE synchronizes with the base station by receiving a primarysynchronization signal (PSS) and a second synchronization signal (SSS)from the base station and obtains information such as a cell identifier(ID). The PSS/SSS used by the MTC UE for the initial cell search may beequal to a PSS/SSS or a resynchronization signal (RSS) of the legacyLTE.

Thereafter, the MTC UE may acquire broadcast information in the cell byreceiving a PBCH signal from the base station.

During the initial cell search, the MTC UE may monitor the state of adownlink channel by receiving a downlink reference signal (DL RS). Thebroadcast information transmitted on the PBCH corresponds to the MIB. Inthe MTC, the MIB is repeated in the first slot of subframe #0 of a radioframe and other subframes (subframe #9 in FDD and subframe #5 in theTDD).

The PBCH repetition is performed such that the same constellation pointis repeated on different OFDM symbols to estimate an initial frequencyerror before attempting PBCH decoding.

FIGS. 14A and 14B illustrate an example of system informationtransmissions in MTC.

Specifically, FIG. 14A illustrates an example of a repetition patternfor subframe #0 in FDD and a frequency error estimation method for anormal CP and repeated symbols, and FIG. 14B illustrates an example oftransmission of an SIB-BR on a wideband LTE channel.

Five reserved bits in the MIB are used in the MTC to transmit schedulinginformation for a new system information block for bandwidth reduceddevice (SIB1-BR) including a time/frequency location and a TBS.

The SIB-BR is transmitted on a PDSCH directly without any relatedcontrol channels.

The SIB-BR is maintained without change for 512 radio frames (5120 ms)to allow a large number of subframes to be combined.

Table 9 shows an example of the MIB.

TABLE 9 -- ASN1START MasterInformationBlock ::= SEQUENCE { dl-BandwidthENUMERATED { n6, n15, n25, n50, n75, n100}, phich-Config PHICH-Config,systemFrameNumber BIT STRING (SIZE (8)), schedulingInfoSIB1-BR-r13INTEGER (0..31), systemInfoUnchanged-BR-r15 BOOLEAN, spare BIT STRING(SIZE (4)) } -- ASN1STOP

In Table 9, the schedulingInfoSIB1-BR field indicates the index of atable that defines SystemInformationBlockType1-BR schedulinginformation. The zero value means that SystemInformationBlockType1-BR isnot scheduled. The overall function and information carried bySystemInformationBlockType1-BR (or SIB1-BR) is similar to SIB1 of thelegacy LTE. The contents of SIB1-BR may be categorized as follows: (1)PLMN; (2) cell selection criteria; and (3) scheduling information forSIB2 and other SIBs.

After completing the initial cell search, the MTC UE may acquire moredetailed system information by receiving a MPDCCH and a PDSCH based oninformation in the MPDCCH in step S1302. The MPDCCH has the followingfeatures: (1) The MPDCCH is very similar to the EPDCCH; (2) The MPDCCHmay be transmitted once or repeatedly (the number of repetitions isconfigured through higher layer signaling); (3) Multiple MPDCCHs aresupported and a set of MPDCCHs are monitored by the UE; (4) the MPDCCHis generated by combining enhanced control channel elements (eCCEs), andeach CCE includes a set of REs; and (5) the MPDCCH supports an RA-RNTI,SI-RNTI, P-RNTI, C-RNTI, temporary C-RNTI, and semi-persistentscheduling (SPS)C-RNTI.

To complete the access to the base station, the MTC UE may perform arandom access procedure in steps S1303 to S1306. The basic configurationof an RACH procedure is carried by SIB2. SIB2 includes parametersrelated to paging. A paging occasion (PO) is a subframe in which theP-RNTI is capable of being transmitted on the MPDCCH. When a P-RNTIPDCCH is repeatedly transmitted, the PO may refer to a subframe whereMPDCCH repetition is started. A paging frame (PF) is one radio frame,which may contain one or multiple POs. When DRX is used, the MTC UEmonitors one PO per DRX cycle. A paging narrowband (PNB) is onenarrowband, on which the MTC UE performs paging message reception.

To this end, the MTC UE may transmit a preamble on a PRACH (S1303) andreceive a response message (e.g., random access response (RAR)) for thepreamble on the MPDCCH and the PDSCH related thereto (S1304). In thecase of contention-based random access, the MTC UE may perform acontention resolution procedure including transmission of an additionalPRACH signal (S1305) and reception of a MPDCCH signal and a PDSCH signalrelated thereto (S1306). In the MTC, the signals and messages (e.g., Msg1, Msg 2, Msg 3, and Msg 4) transmitted during the RACH procedure may berepeatedly transmitted, and a repetition pattern may be configureddifferently depending on coverage enhancement (CE) levels. Msg 1 mayrepresent the PRACH preamble, Msg 2 may represent the RAR, Msg 3 mayrepresent uplink transmission for the RAR at the MTC UE, and Msg 4 mayrepresent downlink transmission for Msg 3 from the base station.

For random access, signaling of different PRACH resources and differentCE levels is supported. This provides the same control of the near-fareffect for the PRACH by grouping UEs that experience similar path losstogether. Up to four different PRACH resources may be signaled to theMTC UE.

The MTC UE measures RSRP using a downlink RS (e.g., CRS, CSI-RS, TRS,etc.) and selects one of random access resources based on themeasurement result. Each of four random access resources has anassociated number of PRACH repetitions and an associated number of RARrepetitions.

Thus, the MTC UE in poor coverage requires a large number of repetitionsso as to be detected by the base station successfully and needs toreceive as many RARs as the number of repetitions such that the coveragelevels thereof are satisfied.

The search spaces for RAR and contention resolution messages are definedin the system information, and the search space is independent for eachcoverage level.

A PRACH waveform used in the MTC is the same as that in the legacy LTE(for example, OFDM and Zadoff-Chu sequences).

After performing the above-described processes, the MTC UE may performreception of an MPDCCH signal and/or a PDSCH signal (S1307) andtransmission of a PUSCH signal and/or a PUCCH signal (S1308) as a normaluplink/downlink signal transmission procedure. Control information thatthe MTC UE transmits to the base station is commonly referred to asuplink control information (UCI). The UCI includes a HARQ-ACK/NACK,scheduling request, channel quality indicator (CQI), precoding matrixindicator (PMI), rank indicator (RI), etc.

When the MTC UE has established an RRC connection, the MTC UE blindlydecodes the MPDCCH in a configured search space to obtain uplink anddownlink data assignments.

In the MTC, all available OFDM symbols in a subframe are used totransmit DCI. Accordingly, time-domain multiplexing is not allowedbetween control and data channels in the subframe. Thus, thecross-subframe scheduling may be performed between the control and datachannels as described above.

If the MPDCCH is last repeated in subframe #N, the MPDCCH schedules aPDSCH assignment in subframe #N+2.

DCI carried by the MPDCCH provides information for how many times theMPDCCH is repeated so that the MTC UE may know the number of repetitionswhen PDSCH transmission is started.

The PDSCH assignment may be performed on different narrowbands. Thus,the MTC UE may need to perform retuning before decoding the PDSCHassignment.

For uplink data transmission, scheduling follows the same timing as thatof the legacy LTE. The last MPDCCH in subframe #N schedules PUSCHtransmission starting in subframe #N+4.

FIG. 15 illustrates an example of scheduling for each of MTC and legacyLTE.

A legacy LTE assignment is scheduled using the PDCCH and uses theinitial OFDM symbols in each subframe. The PDSCH is scheduled in thesame subframe in which the PDCCH is received.

On the other hand, the MTC PDSCH is cross-subframe scheduled, and onesubframe is defined between the MPDCCH and PDSCH to allow MPDCCHdecoding and RF retuning.

MTC control and data channels may be repeated for a large number ofsubframes to be decoded in an extreme coverage condition. Specifically,the MTC control and data channels may be repeated for a maximum of 256subframes for the MPDCCH and a maximum of 2048 subframes for the PDSCH

F. Narrowband-Internet of Things (NB-IoT)

The NB-IoT may refer to a system for providing low complexity and lowpower consumption based on a system bandwidth (BW) corresponding to onephysical resource block (PRB) of a wireless communication system (e.g.,LTE system, NR system, etc.).

Herein, the NB-IoT may be referred to as another terminology such as‘NB-LTE’, ‘NB-IoT enhancement’, ‘further enhanced NB-IoT’, or ‘NB-NR’.The NB-IoT may be replaced with a term defined or to be defined in the3GPP standards. For convenience of description, all types of NB-IoT iscommonly referred to as ‘NB-IoT’.

The NB-IoT may be used to implement the IoT by supporting an MTC device(or MTC UE) in a cellular system. Since one PRB of the system BW isallocated for the NB-IoT, frequency may be efficiently used. Inaddition, considering that in the NB-IoT, each UE recognizes a singlePRB as one carrier, the PRB and carrier described herein may beconsidered to have the same meaning.

Although the present disclosure describes frame structures, physicalchannels, multi-carrier operation, operation modes, and general signaltransmission and reception of the NB-IoT based on the LTE system, it isapparent that the present disclosure is applicable to thenext-generation systems (e.g., NR system, etc.). In addition, thedetails of the NB-IoT described in the present disclosure may be appliedto the MTC, which has similar purposes (e.g., low power, low cost,coverage enhancement, etc.).

1) Frame Structure and Physical Resource of NB-IoT

The NB-IoT frame structure may vary depending on subcarrier spacing.

FIGS. 16 and 17 illustrate examples of NB-IoT frame structures accordingto subcarrier spacing (SCS). Specifically, FIG. 16 illustrates a framestructure with SCS of 15 kHz, and FIG. 17 illustrates a frame structurewith SCS of 3.75 kHz. However, the NB-IoT frame structure is not limitedthereto, and different SCS (e.g., 30 kHz, etc.) may be applied to theNB-IoT by changing the time/frequency unit.

Although the present disclosure describes the NB-IoT frame structurebased on the LTE frame structure, this is merely for convenience ofdescription and the present disclosure is not limited thereto. That is,the embodiments of the present disclosure are applicable to the NB-IoTbased on the frame structure of the next-generation system (e.g., NRsystem).

Referring to FIG. 16, the NB-IoT frame structure for the 15 kHzsubcarrier spacing is the same as the frame structure of the legacysystem (LTE system). Specifically, a 10 ms NB-IoT frame may include 10NB-IoT subframes of 1 ms each, and the 1 ms NB-IoT subframe may includetwo NB-IoT slots, each having a duration of 0.5 ms. Each 0.5 ms NB-IoTslot ms may include 7 OFDM symbols.

Referring to FIG. 17, a 10 ms NB-IoT frame may include five NB-IoTsubframes of 2 ms each, and the 2 ms NB-IoT subframe may include 7 OFDMsymbols and one guard period (GP). The 2 ms NB-IoT subframe may beexpressed as an NB-IoT slot or an NB-IoT resource unit (RU).

Hereinafter, downlink and uplink physical resources for the NB-IoT willbe described.

The NB-IoT downlink physical resource may be configured based onphysical resources of other communication systems (e.g., LTE system, NRsystem, etc.) except that the system BW is composed of a specific numberof RBs (e.g., one RB=180 kHz). For example, when NB-IoT downlinksupports only the 15 kHz subcarrier spacing as described above, theNB-IoT downlink physical resource may be configured by limiting theresource grid of the LTE system illustrated in FIG. 6 to one RB (i.e.,one PRB) in the frequency domain.

The NB-IoT uplink physical resource may be configured by limiting to thesystem bandwidth to one RB as in the NB-IoT downlink. For example, whenNB-IoT uplink supports the 15 kHz and 3.75 kHz subcarrier spacing asdescribed above, a resource grid for the NB-IoT uplink may berepresented as shown in FIG. 18. The number of subcarriers N_(sc) ^(UL)and the slot period T_(slot) may be given in Table 10 below.

FIG. 18 illustrates an example of the resource grid for NB-IoT uplink.

TABLE 10 Subcarrier spacing N_(sc) ^(UL) T_(slot) Δf = 3.75 kHz 48 61440· T_(s) Δf = 15 kHz 12 15360 · T_(s)

A resource unit (RU) for the NB-IoT uplink may include SC-FDMA symbolsin the time domain and N_(symb) ^(UL)N_(slots) ^(UL) consecutivesubcarriers in the frequency domain. In frame structure type 1 (i.e.,FDD), the values of N_(sc) ^(RU) and N_(symb) ^(UL) may be given inTable 11 below. In frame structure type 2 (i.e., TDD), the values ofN_(sc) ^(RU) and N_(symb) ^(UL) may be given in Table 12.

TABLE 11 NPUSCH format Δf N_(sc) ^(RU) N_(slots) ^(UL) N_(symb) ^(UL) 13.75 kHz 1 16 7 15 kHz 1 16 3 8 6 4 12 2 2 3.75 kHz 1 4 15 kHz 1 4

TABLE 12 Supported uplink- NPUSCH downlink format Δf configurationsN_(sc) ^(RU) N_(slots) ^(UL) N_(symb) ^(UL) 1 3.75 kHz 1, 4 1 16 7 15kHz 1, 2, 3, 4, 5 1 16 3 8 6 4 12 2 2 3.75 kHz 1, 4 1 4 15 kHz 1, 2, 3,4, 5 1 4

2) Physical Channels of NB-IoT

A base station and/or UE that support the NB-IoT may be configured totransmit and receive physical channels and signals different from thosein the legacy system. Hereinafter, the physical channels and/or signalssupported in the NB-IoT will be described in detail.

First, the NB-IoT downlink will be described. For the NB-IoT downlink,an OFDMA scheme with the 15 kHz subcarrier spacing may be applied.Accordingly, orthogonality between subcarriers may be provided, therebysupporting coexistence with the legacy system (e.g., LTE system, NRsystem, etc.).

To distinguish the physical channels of the NB-IoT system from those ofthe legacy system, ‘N (narrowband)’ may be added. For example, DLphysical channels may be defined as follows: ‘narrowband physicalbroadcast channel (NPBCH)’, ‘narrowband physical downlink controlchannel (NPDCCH)’, ‘narrowband physical downlink shared channel(NPDSCH)’, etc. DL physical signals may be defined as follows:‘narrowband primary synchronization signal (NPSS)’, ‘narrowbandsecondary synchronization signal (NSSS)’, ‘narrowband reference signal(NRS)’, ‘narrowband positioning reference signal (NPRS)’, ‘narrowbandwake-up signal (NWUS)’, etc.

Generally, the above-described downlink physical channels and physicalsignals for the NB-IoT may be configured to be transmitted based ontime-domain multiplexing and/or frequency-domain multiplexing.

The NPBCH, NPDCCH, and NPDSCH, which are downlink channels of the NB-IoTsystem, may be repeatedly transmitted for coverage enhancement.

The NB-IoT uses newly defined DCI formats. For example, the DCI formatsfor the NB-IoT may be defined as follows: DCI format NO, DCI format N1,DCI format N2, etc.

Next, the NB-IoT uplink will be described. For the NB-IoT uplink, anSC-FDMA scheme with the subcarrier spacing of 15 kHz or 3.75 kHz may beapplied. The NB-IoT uplink may support multi-tone and single-tonetransmissions. For example, the multi-tone transmission may support the15 kHz subcarrier spacing, and the single-tone transmission may supportboth the 15 kHz and 3.75 kHz subcarrier spacing.

In the case of the NB-IoT uplink, ‘N (narrowband)’ may also be added todistinguish the physical channels of the NB-IoT system from those of thelegacy system, similarly to the NB-IoT downlink. For example, uplinkphysical channels may be defined as follows: ‘narrowband physical randomaccess channel (NPRACH)’, ‘narrowband physical uplink shared channel(NPUSCH)’, etc. UL physical signals may be defined as follows:‘narrowband demodulation reference signal (NDMRS)’.

The NPUSCH may be configured with NPUSCH format 1 and NPUSCH format 2.For example, NPUSCH format 1 is used for UL-SCH transmission (ortransfer), and NPUSCH format 2 may be used for UCI transmission such asHARQ ACK signaling.

The NPRACH, which is a downlink channel of the NB-IoT system, may berepeatedly transmitted for coverage enhancement. In this case, frequencyhopping may be applied to the repeated transmission.

3) Multi-Carrier Operation in NB-IoT

Hereinafter, the multi-carrier operation in the NB-IoT will bedescribed. The multi-carrier operation may mean that when the basestation and/or UE uses different usage of multiple carriers (i.e.,different types of multiple carriers) in transmitting and receiving achannel and/or a signal in the NB-IoT.

In general, the NB-IoT may operate in multi-carrier mode as describedabove. In this case, NB-IoT carriers may be divided into an anchor typecarrier (i.e., anchor carrier or anchor PRB) and a non-anchor typecarrier (i.e., non-anchor carrier or non-anchor PRB).

From the perspective of the base station, the anchor carrier may mean acarrier for transmitting the NPDSCH that carries the NPSS, NSSS, NPBCH,and SIB (N-SIB) for initial access. In other words, in the NB-IoT, thecarrier for initial access may be referred to as the anchor carrier, andthe remaining carrier(s) may be referred to as the non-anchor carrier.In this case, there may be one or multiple anchor carriers in thesystem.

4) Operation Mode of NB-IoT

The operation mode of the NB-IoT will be described. The NB-IoT systemmay support three operation modes. FIGS. 19A to 19C illustrate anexamples of operation modes supported in the NB-IoT system. Although thepresent disclosure describes the NB-IoT operation mode based on the LTEband, this is merely for convenience of description and the presentdisclosure is also applicable to other system bands (e.g., NR systemband).

FIG. 19A illustrates an in-band system, FIG. 19B illustrates aguard-band system, and FIG. 19C illustrates a stand-alone system. Thein-band system, guard-band system, and stand-alone system may bereferred to as in-band mode, guard-band mode, and stand-alone mode,respectively.

The in-band system may mean a system or mode that uses one specific RB(PRB) in the legacy LTE band for the NB-IoT. To operate the in-bandsystem, some RBs of the LTE system carrier may be allocated.

The guard-band system may mean a system or mode that uses a spacereserved for the guard band of the legacy LTE band for the NB-IoT. Tooperate the guard-band system, the guard band of the LTE carrier whichis not used as the RB in the LTE system may be allocated. For example,the legacy LTE band may be configured such that each LTE band has theguard band of minimum 100 kHz at the end thereof. In order to use 200kHz, two non-contiguous guard bands may be used.

The in-band system and the guard-band system may operate in a structurewhere the NB-IoT coexists in the legacy LTE band.

Meanwhile, the stand-alone system may mean a system or mode independentfrom the legacy LTE band. To operate the stand-alone system, a frequencyband (e.g., reallocated GSM carrier) used in a GSM EDGE radio accessnetwork (GERAN) may be separately allocated.

The above three operation modes may be applied independently, or two ormore operation modes may be combined and applied.

5) General Signal Transmission and Reception Procedure in NB-IoT

FIG. 20 illustrates an example of physical channels available in theNB-IoT and a general signal transmission method using the same. In awireless communication system, an NB-IoT UE may receive information froma base station in downlink (DL) and transmit information to the basestation in uplink (UL). In other words, the base station may transmitthe information to the NB-IoT UE in downlink and receive the informationfrom the NB-IoT UE in uplink in the wireless communication system.

Information transmitted and received between the base station and theNB-IoT UE may include various data and control information, and variousphysical channels may be used depending on the type/usage of informationtransmitted and received therebetween. The NB-IoT signal transmissionand reception method described with reference to FIG. 20 may beperformed by the aforementioned wireless communication apparatuses(e.g., base station and UE in FIG. 11).

When the NB-IoT UE is powered on or enters a new cell, the NB-IoT UE mayperform initial cell search (S11). The initial cell search involvesacquisition of synchronization with the base station. Specifically, theNB-IoT UE may synchronize with the base station by receiving an NPSS andan NSSS from the base station and obtain information such as a cell ID.Thereafter, the NB-IoT UE may acquire information broadcast in the cellby receiving an NPBCH from the base station. During the initial cellsearch, the NB-IoT UE may monitor the state of a downlink channel byreceiving a downlink reference signal (DL RS).

In other words, when the NB-IoT UE enters the new cell, the BS mayperform the initial cell search, and more particularly, the base stationmay synchronize with the UE. Specifically, the base station maysynchronize with the NB-IoT UE by transmitting the NPSS and NSSS to theUE and transmit the information such as the cell ID. The base stationmay transmit the broadcast information in the cell by transmitting (orbroadcasting) the NPBCH to the NB-IoT UE. The BS may transmit the DL RSto the NB-IoT UE during the initial cell search to check the downlinkchannel state.

After completing the initial cell search, the NB-IoT UE may acquire moredetailed system information by receiving a NPDCCH and a NPDSCH relatedto thereto (S12). In other words, after the initial cell search, thebase station may transmit the more detailed system information bytransmitting the NPDCCH and the NPDSCH related to thereto to the NB-IoTUE.

Thereafter, the NB-IoT UE may perform a random access procedure tocomplete the access to the base station (S13 to S16).

Specifically, the NB-IoT UE may transmit a preamble on an NPRACH (S13).As described above, the NPRACH may be repeatedly transmitted based onfrequency hopping for coverage enhancement. In other words, the basestation may (repeatedly) receive the preamble from the NB-IoT UE overthe NPRACH.

Then, the NB-IoT UE may receive a random access response (RAR) for thepreamble from the base station on the NPDCCH and the NPDSCH relatedthereto (S14). That is, the base station may transmit the random accessresponse (RAR) for the preamble to the base station on the NPDCCH andthe NPDSCH related thereto.

The NB-IoT UE may transmit an NPUSCH using scheduling information in theRAR (S15) and perform a contention resolution procedure based on theNPDCCH and the NPDSCH related thereto (S16). That is, the base stationmay receive the NPUSCH from the NB-IoT UE based on the schedulinginformation in the RAR and perform the contention resolution procedure.

After performing the above-described processes, the NB-IoT UE mayperform NPDCCH/NPDSCH reception (S17) and NPUSCH transmission (S18) as anormal UL/DL signal transmission procedure. After the above-describedprocesses, the base station may transmit the NPDCCH/NPDSCH to the NB-IoTUE and receive the NPUSCH from the NB-IoT UE during the normaluplink/downlink signal transmission procedure.

In the NB-IoT, the NPBCH, NPDCCH, NPDSCH, etc. may be repeatedlytransmitted for the coverage enhancement as described above. Inaddition, UL-SCH (normal uplink data) and UCI may be transmitted on theNPUSCH. In this case, the UL-SCH and UCI may be configured to betransmitted in different NPUSCH formats (e.g., NPUSCH format 1, NPUSCHformat 2, etc.)

As described above, the UCI means control information transmitted fromthe UE to the base station. The UCI may include the HARQ ACK/NACK,scheduling request (SR), CSI, etc. The CSI may include the CQI, PMI, RI,etc. Generally, the UCI may be transmitted over the NPUSCH in the NB-IoTas described above. In particular, the UE may transmit the UCI on theNPUSCH periodically, aperiodically, or semi-persistently according tothe request/indication from the network (e.g., base station).

6) Initial Access Procedure in NB-IoT

The procedure in which the NB-IoT UE initially accesses the BS isbriefly described in the section “General Signal Transmission andReception Procedure in NB-IoT”. Specifically, the above procedure may besubdivided into a procedure in which the NB-IoT UE searches for aninitial cell and a procedure in which the NB-IoT UE obtains systeminformation.

FIG. 21 illustrates a particular procedure for signaling between a UEand a BS (e.g., NodeB, eNodeB, eNB, gNB, etc.) for initial access in theNB-IoT. In the following, a normal initial access procedure, anNPSS/NSSS configuration, and acquisition of system information (e.g.,MIB, SIB, etc.) in the NB-IoT will be described with reference to FIG.21.

FIG. 21 illustrates an example of the initial access procedure in theNB-IoT. The name of each physical channel and/or signal may varydepending on the wireless communication system to which the NB-IoT isapplied. For example, although the NB-IoT based on the LTE system isconsidered in FIG. 21, this is merely for convenience of description anddetails thereof are applicable to the NB-IoT based on the NR system. Thedetails of the initial access procedure are also applicable to the MTC.

Referring to FIG. 21, the NB-IoT UE may receive a narrowbandsynchronization signal (e.g., NPSS, NSSS, etc.) from the base station(S2110 and S2120). The narrowband synchronization signal may betransmitted through physical layer signaling.

The NB-IoT UE may receive a master information block (MIB) (e.g.,MIB-NB) from the base station on an NPBCH (S2130). The MIB may betransmitted through higher layer signaling (e.g., RRC signaling).

The NB-IoT UE may receive a system information block (SIB) from the basestation on an NPDSH (S2140 and S2150). Specifically, the NB-IoT UE mayreceive SIB1-NB, SIB2-NB, etc. on the NPDSCH through the higher layersignaling (e.g., RRC signaling). For example, SIB1-NB may refer tosystem information with high priority among SIBs, and SIB2-NB may referto system information with lower priority than SIB1-NB.

The NB-IoT may receive an NRS from the BS (S2160), and this operationmay be performed through physical layer signaling.

7) Random Access Procedure in NB-IoT

The procedure in which the NB-IoT UE performs random access to the basestation is briefly described in the section “General Signal Transmissionand Reception Procedure in NB-IoT”. Specifically, the above proceduremay be subdivided into a procedure in which the NB-IoT UE transmits apreamble to the base station and a procedure in which the NB-IoTreceives a response for the preamble.

FIG. 22 illustrates a particular procedure for signaling between a UEand a base station (e.g., NodeB, eNodeB, eNB, gNB, etc.) for randomaccess in the NB-IoT. In the following, detail of the random accessprocedure in the NB-IoT will be described based on messages (e.g., msg1,msg2, msg3, msg4) used therefor.

FIG. 22 illustrates an example of the random access procedure in theNB-IoT. The name of each physical channel, physical signal, and/ormessage may vary depending on the wireless communication system to whichthe NB-IoT is applied. For example, although the NB-IoT based on the LTEsystem is considered in FIG. 22, this is merely for convenience ofdescription and details thereof are applicable to the NB-IoT based onthe NR system. The details of the initial access procedure are alsoapplicable to the MTC.

Referring to FIG. 22, the NB-IoT may be configured to supportcontention-based random access.

First, the NB-IoT UE may select an NPRACH resource based on the coveragelevel of the corresponding UE. The NB-IoT UE may transmit a randomaccess preamble (i.e., message 1, msg1) to the base station on theselected NPRACH resource.

The NB-IoT UE may monitor an NPDCCH search space to search for an NPDCCHfor DCI scrambled with an RA-RNTI (e.g., DCI format N1). Upon receivingthe NPDCCH for the DCI scrambled with the RA-RNTI, the UE may receive anRAR (i.e., message 2, msg2) from the base station on an NPDSCH relatedto the NPDCCH. The NB-IoT UE may obtain a temporary identifier (e.g.,temporary C-RNTI), a timing advance (TA) command, etc. from the RAR. Inaddition, the RAR may also provide an uplink grant for a scheduledmessage (i.e., message 3, msg3).

To start a contention resolution procedure, the NB-IoT UE may transmitthe scheduled message to the base station. Then, the base station maytransmit an associated contention resolution message (i.e., message 4,msg4) to the NB-IoT UE in order to inform that the random accessprocedure is successfully completed.

By doing the above, the base station and the NB-IoT UE may complete therandom access.

8) DRX Procedure in NB-IoT

While performing the general signal transmission and reception procedureof the NB-IoT, the NB-IoT UE may transit to an idle state (e.g., RRCIDLE state) and/or an inactive state (e.g., RRC INACTIVE state) toreduce power consumption. The NB-IoT UE may be configured to operate inDRX mode after transiting to the idle state and/or the inactive state.For example, after transiting to the idle state and/or the inactivestate, the NB-IoT UE may be configured to monitor an NPDCCH related topaging only in a specific subframe (frame or slot) according to a DRXcycle determined by the BS. Here, the NPDCCH related to paging may referto an NPDCCH scrambled with a P-RNTI.

FIG. 23 illustrates an example of DRX mode in an idle state and/or aninactive state.

A DRX configuration and indication for the NB-IoT UE may be provided asshown in FIG. 24. That is, FIG. 24 illustrates an example of a DRXconfiguration and indication procedure for the NB-IoT UE. However, theprocedure in FIG. 24 is merely exemplary, and the methods proposed inthe present disclosure are not limited thereto.

Referring to FIG. 24, the NB-IoT UE may receive DRX configurationinformation from the base station (e.g., NodeB, eNodeB, eNB, gNB, etc.)(S2410). In this case, the UE may receive the information from the basestation through higher layer signaling (e.g., RRC signaling). The DRXconfiguration information may include DRX cycle information, a DRXoffset, configuration information for DRX-related timers, etc.

Thereafter, the NB-IoT UE may receive a DRX command from the basestation (S2420). In this case, the UE may receive the DRX command fromthe base station through higher layer signaling (e.g., MAC-CEsignaling).

Upon receiving the DRX command, the NB-IoT UE may monitor an NPDCCH in aspecific time unit (e.g., subframe, slot, etc.) based on the DRX cycle(S2430). The NPDCCH monitoring may mean a process of decoding a specificportion of the NPDCCH based on a DCI format to be received in acorresponding search space and scrambling a corresponding CRC with aspecific predefined RNTI value in order to check whether the scrambledCRC matches (i.e. corresponds to) a desired value.

When the NB-IoT UE receives its paging ID and/or information indicatingthat system information is changed over the NPDCCH during the processshown in FIG. 24, the NB-IoT UE may initialize (or reconfigure) theconnection (e.g., RRC connection) with the base station (for example,the UE may perform the cell search procedure of FIG. 20). Alternatively,the NB-IoT UE may receive (or obtain) new system information from thebase station (for example, the UE may perform the system informationacquisition procedure of FIG. 20).

G. Proposals for Configuring Offset Between Signal and Related Channel

The present disclosure proposes methods of, when a specific signal orchannel is used to indicate information for another signal or channel,establishing a relationship between the specific signal or channelcarrying the information and the another signal or channel to which theinformation is targeted. In a particular example, the specific signalcarrying the information may be a wake-up signal (WUS) indicatingwhether the another signal or channel to which the information istargeted will be transmitted or not. The another channel to which theinformation is targeted may be, for example, an NPDCCH (or PDCCH orMPDCCH) for paging. In this particular example, the WUS may be used toprovide information indicating whether the paging NPDCCH will betransmitted. In the following description, a specific signal or channelused to indicate information for another signal or channel is referredto as “signal-A”, and a signal or channel corresponding to theinformation carried by signal-A is referred to as “channel-B”. While thefollowing description is given mainly in the context of a relationshipbetween the WUS and the paging NPDCCH, for the convenience ofdescription, it is apparent that the description can be applied to othersituations in which a specific signal or channel is generally used toindicate information for another signal or channel. The followingproposed methods of the present disclosure may be performedindependently, or one or more of the methods may be performed incombination.

In the present disclosure, a case in which a transmitting time ofsignal-A is determined to be a position relative to a transmitting timeof signal-B is considered. In general, once the transmitting time ofchannel-B is determined, the transmitting time of signal-A may bedetermined to be a position prior to the transmitting time of channel-B.The accurate transmitting time of signal-A may be determined based on anoffset from the transmitting time of channel-B.

G.1 Offset Between Signal-A and Channel-B

(Method 1) when a Transmission Starting Time of Signal-A is Determinedby an Offset from a Transmission Starting Time of Channel-B, a Value ofthe Offset May be Determined by a Function of a Transmission Duration ofSignal-A.

When the transmission starting time of signal-A is determined by anoffset from the transmission starting time of channel-B, the offsetshould be large enough to enable transmission of signal-A. For example,when the transmission duration of signal-A requires L subframes, theoffset should be equal to or larger than at least L subframes. Further,the offset should be determined in consideration of the length of a timeperiod during which transmission is impossible, which exists between thetransmission starting time and the transmission ending time of signal-A.In DL NB-IoT transmission, for example, the WUS is transmitted only invalid DL NB-IoT subframes unused for transmission of a systeminformation block (SIB) (or system information), and the other subframesmay be treated as invalid subframes. In this case, when a maximumduration required to transmit the WUS is L subframes, the transmissionstarting time of the WUS should be determined such that L or more validDL NB-IoT subframes can be included.

To overcome the above problem, the present disclosure proposes a methodof determining a value of an offset from channel-B, based on which thetransmission starting time of signal-A is determined, by a function ofthe transmission duration of signal-A.

The function of determining the offset may be in the form of amultiplication of the transmission duration of signal-A and a scalingfactor. For example, when signal-A is the WUS and channel-B is thepaging NPDCCH, it may be assumed that the scaling factor is determinedto be alpha, with the maximum duration of the WUS configured as L. Anoffset t_(offset-alpha) for determining the transmission starting timeof signal-A may be determined by Equation 3.t _(offset-alpha) =┌L*alpha┐  Equation 3

In Equation 3, ┌x┐ represents an operation of obtaining the ceiling ofx. Herein, alpha may have a real number value larger than 1.

In Equation 3, the scaling factor alpha may be configured throughhigher-layer signal such as an SIB or RRC signaling by a base station.In this case, it is advantageous in that the base station can adjust theoffset between signal-A and channel-B with increased flexibility.Alternatively, the scaling factor alpha of Equation 3 may be a valueimplicitly determined by another parameter. For example, the parametermay be an available transmission duration of signal-A per time unit. Ina particular example, when the transmission starting time of the WUS isto be determined in NB-IoT, the scaling factor alpha used to determinethe offset may be determined depending on the number of valid subframesin a bitmap for indicating valid DL subframes.

Alternatively, the function of determining the offset may be in the formof a table for determining a predefined offset value according to atransmission duration of signal-A. The table may indicate (1) the offsetvalue directly or (2) a scaling factor to be multiplied by thetransmission duration of signal-A to calculate the offset value. One ormore offset values may correspond to the transmission duration ofsignal-A in the table. In this case, a criteria of selecting an offsetvalue from the table may be (1) using a value indicated throughhigher-layer signaling such as an SIB or RRC signaling or (2)determining based on another parameter value (e.g., a ratio of valid DLsubframes in the bitmap).

FIG. 25 illustrates an exemplary case in which the offset between thetransmission starting time of signal-A and the transmission startingtime of channel-B is calculated as t_(offset-alpha) according to theabove-described method.

A specific example to which the above method is applied may be given asfollows. In this example, it is assumed that there is a bitmapindicating positions of subframes that can be used for DL transmission,the total number of DL subframes representable by the bitmap is X, andthe number of subframes available for transmission of signal-A among theX DL subframes is Y. The scaling factor may be determined by a functionof X and Y. For example, a table to be used may be determined based onX, and a value may be selected from the table based on Y. This method isadvantageous in that values suitable for respective situations may bepredetermined, rather than a UE stores the table. In another example,the scaling factor may be defined by the ratio between X and Y. In amore specific example, the scaling factor alpha may be defined asc+d*Y/X where c may be a constant added to set an offset related only tothe transmission duration of signal-A irrespective of the ratio betweenX and Y, and d may be a constant multiplied to correct the relationshipbetween the ratio between X and Y and the offset. Herein, c and d may beselected differently according to the length of X. Alternatively, c andd may be applied differently to an anchor carrier and a non-anchorcarrier. This operation may be intended to reflect possible differenttransmission overheads which are always imposed on the anchor carrierand the non-anchor carrier.

(Method 2) when a Transmission Starting Time of Signal-A is Determinedby an Offset from a Transmission Starting Time of Channel-B, a Value ofthe Offset May be Determined by a Combination of an Additional Offsetand a Function of a Transmission Duration of Signal-A.

After the UE obtains information for channel-B from signal-A, the UE mayneed a certain amount of time or more to prepare for reception ofchannel-B. For example, when signal-A is a signal detectable withoutchannel estimation, the UE may need a warm-up period to increase theaccuracy of channel estimation for the reception of channel-B. InNB-IoT, for example, a UE is allowed to monitor an NRS in 10 valid DLsubframe periods before a search space carrying a paging NPDCCH startsin order to monitor the NPDCCH for paging.

When a method of Method 1 is used, the number of signalings orparameters for determining an offset may be limited, which may in turncause limitation of the granularity of a gap between the transmissionending time of signal-A and the transmission starting time of channel-B.For example, in NB-IoT, the requirement of 10 valid DL subframes formonitoring a paging NPDCCH may not be satisfied. In another example,when the granularity of the transmission duration of signal-A is large,it may be disadvantageous in that the gap increases in proportion to thetransmission duration of signal-A. In particular example, for NB-IoT,when the transmission starting time of the WUS is defined by an offsetfrom the transmission starting time of the paging NPDCCH and the offsetis determined by a multiplication of the maximum duration of the WUS andthe scaling factor alpha, there may be a twofold gap difference betweena maximum duration of 1024 subframes for the WUS and a maximum durationof 512 subframes for the WUS, with respect to the same alpha value.

To overcome the above problem, the present disclosure proposes a methodof determining an offset from channel-B by an additional offset valueand a function of the transmission duration of signal-A, where thetransmission starting time of signal-A is determined based on the offsetfrom channel-B. An offset t_(offset-sum) for determining thetransmission starting time of signal-A may be determined by Equation 4below.t _(offset-sum) =t _(offset-alpha) +t _(offset-beta)  Equation 4

In Equation 4, t_(offset-alpha) may be obtained using a method describedin Method 1.

In Equation 4, t_(offset-beta) may be a value predetermined by thestandards. This may be intended to ensure an offset value equal to orlarger than a certain value all the time without additional signaling orinterpretation. Alternatively, t_(offset-beta) in Equation 4 may beindicated by higher-layer signaling such as an SIB or RRC signaling.This may be intended to ensure a minimum required gap or reduce anunnecessary size of gap by allowing an offset suitable for a situationto be configured by the network. Alternatively, t_(offset-beta) inEquation 4 may be determined by another parameter. For example, theparameter may be the transmission duration of signal-A. This may beintended to predetermine required offsets according to transmissiondurations of signal-A and reduce unnecessary signaling overhead. Themethods of determining t_(offset-beta) may be used independently or oneor more of the methods may be used in combination.

FIG. 26 illustrates an exemplary case in which the offset between thetransmission starting time of signal-A and the transmission startingtime of channel-B is calculated by a combination of t_(offset-alpha) andt_(offset-beta) in the above-described methods.

(Method 3) in the Case where a Transmission Starting Time of Signal-A isDetermined by an Offset from a Transmission Starting Time of Channel-B,when a Transmission Resource at the Starting Time Indicated by theOffset is Unavailable for Transmission of Signal-A, the TransmissionStarting Time of Signal-A is Postponed to the Position of the ClosestTransmission Resource Available for Transmission of Signal-A Among theSubsequent Transmission Resources.

In operating time-domain/frequency-domain transmission resources by anetwork, when two or more signals or channels used for differentpurposes need the same transmission resource, the network may allow thetransmission resource only for a specific signal or channel, whileprohibiting the use of the transmission resource for the other signalsor channels. For example, when a specific signal requires periodictransmission and has importance over the other signals or channels(e.g., a synchronization signal; a PSS/SSS/PBCH or NPSS/NSSS/NPBCH), thenetwork may not allow transmission of the signals or channels for otherpurposes in the transmission resource carrying the corresponding signal.In another example, in NB-IoT, the network may divide specific subframesof a specific carrier into valid NB-IoT subframes available for NB-IoTtransmission and invalid NB-IoT subframes unavailable for NB-IoTtransmission, and indicate the valid and invalid NB-IoT subframes to aUE.

To overcome the above problem, the present disclosure proposes a methodof, when the transmission starting time of signal-A determined by anoffset is unavailable for transmission of signal-A, postponing thetransmission starting time of signal-A to the position of the closesttransmission resource available for transmission of signal-A among thesubsequent transmission resources. In NB-IoT, for example, the WUS maybe transmittable only in an NB-IoT DL valid subframe. When the startingtransmission subframe of the WUS indicated by an offset is not an NB-IoTDL valid subframe, the WUS transmission may start in the closest NB-IoTDL valid subframe among the subsequent subframes. The proposed method isadvantageous in that complexity is reduced because the UE and the basestation can determine the transmitting time of signal-A at a timedetermined based on an offset without preliminarily calculating areference for determining the transmitting time of signal-A.

FIG. 27 illustrates an exemplary method of postponing the transmissionstarting time of signal-A, when the transmission starting time ofsignal-A is determined by an offset from the transmission starting timeof channel-B in the above-described method and a correspondingtransmission resource is unavailable (invalid).

(Method 4) in the Case where a Transmission Starting Time of Signal-A isDetermined by an Offset from a Transmission Starting Time of Channel-B,when a Transmission Resource at the Starting Time Indicated by theOffset is Unavailable for Transmission of Signal-A, the TransmissionStarting Time of Signal-A is Advanced to the Position of the ClosestTransmission Resource Available for Transmission of Signal-A Among thePreceding Transmission Resources.

In operating time-domain/frequency-domain transmission resources by anetwork, when two or more signals or channels used for differentpurposes need the same transmission resource, the network may allow thetransmission resource only for a specific signal or channel, whileprohibiting the use of the transmission resource for the other signalsor channels. For example, when a specific signal requires periodictransmission and has importance over the other signals or channels(e.g., a synchronization signal; a PSS/SSS/PBCH or NPSS/NSSS/NPBCH), thenetwork may not allow transmission of the signals or channels for otherpurposes in the transmission resource carrying the corresponding signal.In another example, in NB-IoT, the network may divide specific subframesof a specific carrier into valid NB-IoT subframes available for NB-IoTtransmission and invalid NB-IoT subframes unavailable for NB-IoTtransmission, and indicate the valid and invalid NB-IoT subframes to aUE.

When the transmission starting time of signal-A is postponed to a latertime point as in Method 3, the gap between the transmission ending timeof signal-A and the transmission starting time of channel-B may bereduced, and in an extreme case, the transmission areas of signal-A andchannel-B may overlap with each other.

To overcome the above problem, the present disclosure proposes a methodof, when the transmission starting time of signal-A determined by anoffset is unavailable for transmission of signal-A, advancing thetransmission starting time of signal-A to the position of the closesttransmission resource available for transmission of signal-A among thepreceding transmission resources. In NB-IoT, for example, the WUS may betransmittable only in an NB-IoT DL valid subframe. When the startingtransmission subframe of the WUS determined by an offset is not anNB-IoT DL valid subframe, the WUS transmission may start in the closestNB-IoT DL valid subframe among the preceding subframes. This method isadvantageous in that the gap between the transmission ending time ofsignal-A and the transmission starting time of channel-B is not reduced.

FIG. 28 illustrates an exemplary method of advancing the transmissionstarting time of signal-A, when the transmission starting time ofsignal-A is determined by an offset from the transmission starting timeof channel-B in the above-described method and a correspondingtransmission resource is unavailable (invalid).

(Method 5) in the Case where a Transmission Starting Time of Signal-A isDetermined by an Offset from a Transmission Starting Time of Channel-B,a Minimum Gap May be Ensured Between a Transmission Ending Time ofSignal-A and the Transmission Starting Time of Channel-B.

After obtaining signal-A, the UE may need a warm-up period to preparefor monitoring channel-B. In a particular example, in NB-IoT, the UE mayneed a minimum gap for operating a main receiver and monitoring an NRSbefore a search space carrying a paging NPDCCH starts, in order tomonitor the paging NPDCCH.

When the transmission starting time of signal-A is defined by an offsetfrom the transmission starting time of channel-B, the minimum requiredgap may not be ensured. For example, it may occur that the number oftransmission resources available for transmission of signal-A is smallerthan a required transmission duration of signal-A, in a time periodbetween the transmission starting time of signal-A and a time when arequired gap should start before the transmission starting time ofchannel-B. In a particular example, in NB-IoT, the number of NB-IoT DLvalid subframes between the position of the starting subframe of the WUSdetermined by an offset from the paging NPDCCH and a subframe in whichthe gap should start may be smaller than the maximum duration of theWUS.

To overcome the above problem, the present disclosure proposes a methodof ensuring a minimum gap between the transmission ending time ofsignal-A and the transmission starting time of channel-B. Specifically,transmission of signal-A is allowed only before the starting time of agap and then transmission of signal-A is punctured after the staringtime of the gap.

When a method of Method 5 and a method of Method 2 are used together, anoffset such as t_(offset-beta) defined in Method 2 may be used todetermine a minimum required gap after the transmission starting time ofchannel-B.

FIG. 29 illustrates an exemplary method of ensuring a minimum gapbetween the transmission ending time of signal-A and the transmissionstarting time of channel-B in the above-described method.

(Method 6) when a Transmission Ending Time of Signal-A is Determined byan Offset from a Transmission Starting Time of Channel-B, the Offset Maybe Calculated Only Based on Transmission Resources Available forTransmission of Signal-A.

A method of determining the transmission ending time of signal-A by anoffset from the transmission starting time of channel-B may be used as amethod of determining a transmission position of signal-A. In this case,the transmission starting time of signal-A may be calculated to be aposition prior to the transmission ending time of signal-A by thetransmission duration of signal-A. Herein, the transmission startingtime of signal-A may be determined by calculating the transmissionduration of signal-A only based on transmission resources available fortransmission of signal-A.

After obtaining signal-A, the UE may need a warm-up period to preparefor monitoring channel-B. In a particular example, in NB-IoT, the UE mayneed a minimum gap for operating a main receiver and monitoring an NRSbefore a search space carrying a paging NPDCCH starts, in order tomonitor the paging NPDCCH.

To overcome the above problem, the present disclosure proposes a methodof calculating an offset from the transmission starting time ofchannel-B based on transmission resources available for transmission ofsignal-A, when determining the transmission ending time of signal-A.

G.2 Offset and UE Capability

The transmitting time of signal-A may be determined by a relative offsetfrom the transmitting time of channel-B. The offset may be defined as aninterval between a transmission starting time of signal-A and atransmission starting time of channel-B, or may be defined as aninterval between a transmission ending time of signal-A and thetransmission starting time of channel-B.

Depending on how a UE is implemented, the UE may require a differentprocessing time to detect (or decode) signal-A. Alternatively, dependingon how the UE is implemented, the UE may require a different preparationtime to start monitoring channel-B after completely detecting (ordecoding) signal-A. Therefore, depending on how the UE is implemented,the size of a gap which is the interval between the transmission endingtime of signal-A and the transmission starting time of channel-B mayvary, or an offset that determines the transmitting time of signal-A mayvary. Performance difference of the UE caused by implementationdifference of the UE may be defined as a UE capability and identifiedaccordingly. The UE may have a different required gap size or offsetsize according to its UE capability.

(Method 7) there May be One or More Offset Determination Methods which aBase Station May Configure. The Base Station May Indicate One OffsetDetermination Method to a UE by Higher-Layer Signaling Such as an SIB orRRC Signaling.

A size of required minimum gap between signal-A and channel-B and anoffset value which may determine the required minimum gap may vary undercircumstances, like the above-described problem. For example, when theWUS serves as signal-A and the paging NPDCCH serves as channel-B inNB-IoT, a required gap between the WUS and the paging NPDCCH may rangefrom tens of milliseconds to a few seconds depending on UEimplementation. When the base station indicates an offset byhigher-layer signaling such as an SIB or RRC signaling, interpretationof every gap in the same field may significantly increase overhead.Moreover, an optimized method of determining an offset to support a gapin units of tens of milliseconds may be different from an optimizedmethod of determining an offset to support a gap in units of a fewseconds.

To overcome the above problem, the present disclosure proposes a methodof indicating an offset determination method by higher-layer signalingsuch as an SIB or RRC signaling. For example, when there are two methodsof determining an offset between the transmission starting time ofsignal-A and the transmission starting time of channel-B: option 1 forsupporting a small offset and option 2 for supporting a large offset,the base station may determine and configure an offset in one of option1 and option 2 and indicate the determined option to the UE.

In a specific method to which a method of Method 7 is applied, the basestation may include 1-bit indication information indicating a selectedoffset determination method in higher-layer signaling such as an SIB orRRC signaling. For example, when the 1-bit indication information is 0,the UE may calculate an offset according to option 1, whereas when the1-bit indication information is 1, the UE may calculate an offsetaccording to option 2. When an additional field for determining aspecific offset value is configured in N bits, this field may beinterpreted differently according to the 1-bit indication information.

In another specific method to which the method of Method 7 is applied,the base station may include an N-bit field for determining an offsetbetween signal-A and channel-B in higher-layer signaling such as an SIBor RRC signaling, and configure 2N states representable by the N-bitfield to be used separately for different offset determination methods.For example, one of the 2N states may be used as an informationrepresentation scheme for selecting the method of determining an offsetof a length of a few seconds, and the other (2N−1) states are used as aninformation representation scheme for selecting the method ofdetermining an offset of a length of a few milliseconds. This is becausean offset of a length of a few seconds may be less sensitive to a gapsize than an offset of a length of a few milliseconds and thus require arelatively low-level granularity.

In another specific method to which the method of Method 7 is applied,the base station may indicate only information for an offsetdetermination method used by default, and when the indicated informationsatisfies a specific condition, apply another offset determinationmethod. For example, the specific condition may be that a signaledoffset does not satisfy a minimum required gap between the transmissionending time of signal-A and the transmission starting time of channel-B.Advantageously, the base station may change an offset determinationmethod without additional signaling.

(Method 8) there May be One or More Transmission Positions of Signal-ACorresponding to One Channel-B. A UE May Determine a TransmissionPosition to Monitor Signal-A According to its UE Capability.

As noted from the above-described problem, a minimum required gapbetween signal-A and channel-B and an offset that can determine theminimum required gap may vary depending on how a UE is implemented. Whenan offset for supporting a small gap size is configured, a UE requiringa large gap size may not easily monitor signal-A. On the contrary, whenan offset for supporting a large gap size is configured, a UE to which asmall gap size is enough may experience performance degradation due topower consumption or the like caused by an unnecessary extra gap size.

To overcome the above problem, the present disclosure proposes a methodof configuring one or more transmission positions of signal-A incorrespondence with one channel-B. Different signal-A transmissions maybe distinguished from each other by different offsets, and the UE mayselect a suitable offset based on its UE capability and monitor signal-Aaccording to the selected offset. The UE capability may be determinedbased on a minimum required gap size (or offset size) required for theUE. When the UE reports its UE capability to the base station, the basestation may predict a position at which each UE will monitor signal-Aand thus may transmit signal-A only at a corresponding transmissionposition.

FIG. 30 illustrates an exemplary method of determining an offset betweenthe transmission starting time of signal-A and the transmission startingtime of channel-B according to a UE capability using the above-describedmethod.

When a transmitting time of signal-A is determined based on two offsetsfrom one channel-B, the relatively longer offset is referred to asoffset-long and the relatively shorter offset is referred to asoffset-short in the following description of the present disclosure, forthe convenience of description. To enable a UE to identify the positionsof the transmission starting time and the transmission ending time ofsignal-A which are suitable for its UE capability, the base stationshould signal information for different offsets to the UE. When twodifferent offsets exist for signal-A and are indicated as offset-longand offset-short by higher-layer signaling such as an SIB or RRCsignaling, one of the following sub-methods may be used as a specificmethod of indicating the offsets.

(Sub-Method 8-1)

Each of offset-long and offset-short may be indicated in independentfields of an SIB or RRC signaling. The UE may recognize both informationfor offset-long and information for offset-short, and interpret and usea field suitable for its UE capability. This method is advantageous inthat scheduling flexibility is ensured as much as possible for each ofoffset-long and offset-short without any mutual influence.

(Sub-Method 8-2)

At least one of offset-long and offset-short may be a value fixed by thestandards. For example, a fixed value defined by the standards may beused as offset-long, and offset-short may be a value indicated byhigher-layer signaling such as an SIB or RRC signaling. This is becausethe interval between signal-A and channel-B for offset-long isrelatively long and thus there is no or little effect of schedulingrestriction, whereas the interval between signal-A and channel-B foroffset-short is significantly affected by the number of availabletransmission resources or a communication environment.

(Sub-Method 8-3)

Offset-long and offset-short may be indicated in the same field of anSIB or RRC signaling. In an exemplary specific method, the size ofoffset-short may be indicated by higher-layer signaling, and the size ofoffset-long may be determined by an offset and/or multiple of the sizeof offset-short. In another exemplary specific method, a field forindicating an offset in higher-layer signaling may be interpreteddifferently according to a UE capability. This may be intended to, whenthere is a correlation between a required offset-long size and arequired offset-short size, control both of the offsets, while reducingoverhead based on this property.

(Method 9) There May be One or More Transmission Positions of Channel-BCorresponding to One Transmission Position of Channel-A. A TransmissionPosition of Channel-B to be Monitored by a UE that has ObtainedChannel-A May be Determined According to the UE Capability of the UE.

When as many transmission positions of signal-A for each channel-Btransmission as the number of UE capabilities are required to supportthe multiple UE capabilities, the network may suffer from increasedoverhead for transmission of signal-A and scheduling restriction.

To overcome the above problem, the present disclosure proposes a methodof designating one or more instances of a transmitting time position ofchannel-B corresponding to a transmitting time of signal-A anddetermining a transmitting time of channel-B corresponding totransmission of signal-A according to a UE capability. Like a method ofMethod 8, this method may restrict a transmitting time of signal-A to atransmitting time of signal-A at other position corresponding to atransmitting time of other channel-B, in the situation that there existmultiple instances of a transmitting time of signal-A corresponding toone transmitting time of channel-B. For example, when a transmissionpoint of the WUS corresponding to each paging NPDCCH is predetermined inNB-IoT, a UE which requires offset-short being a short offset isconfigured to monitor the transmission position of the WUS correspondingto an n^(th) paging NPDCCH to determine whether to monitor the n^(th)paging NPDCCH, and a UE which requires offset-long being a long offsetis configured to monitor the transmission position of the WUScorresponding to an (n−1)^(th) paging NPDCCH to determine whether tomonitor the n^(th) paging NPDCCH.

FIG. 31 illustrates an exemplary method of determining an offset betweenthe transmission starting time of signal-A and the transmission startingtime of channel-B according to a UE capability according to theabove-proposed method.

In an exemplary specific method to which the proposed Method 9 isapplied, positions at which channel-B may be transmitted in a DRX cyclemay be configured periodically. In a specific example, a search spaceavailable for transmission of the paging NPDCCH may be configuredaccording to a DRX cycle, and a transmitting time of the WUS may bedetermined to be prior to the transmission starting time of each pagingNPDCCH by a specific offset. Upon receipt of the WUS, a UE requiringoffset-short may expect and monitor the subsequent paging NPDCCH. Uponreceipt of the WUS, a UE requiring offset-long may monitor a pagingNPDCCH in the next DRX cycle (or after X DRX cycles) without monitoringthe subsequent paging NPDCCH. This example may be expressed as Equation5.t _(offset-long) =X*T+t _(offset-short)  Equation 5

In Equation 5, t_(offset-long) represents an offset for a UE with a UEcapability requiring offset-long, and t_(offset-short) represents anoffset for a UE with a UE capability requiring offset-short. Trepresents the size of a DRX cycle for the paging NPDCCH. When X is aninteger (e.g., X=1, 2, . . . ) in the above equation, a UE requiringoffset-long shares a WUS transmitting time of a UE with an offset-shortUE capability sharing the same paging occasion (PO), and the POcorresponding to the WUS is interpreted differently. When X is arational number (e.g., X=½, ¼, . . . ) in Equation 5, a UE requiringoffset-long shares a WUS transmitting time corresponding to a PO foranother UE group (which is identified by UE_ID and determines whether tomonitor a specific PO).

When a method of Method 9 is applied, T may be limited to apredetermined value to prevent a UE applying offset-long from waitingtoo long. For example, a search space available for transmission of thepaging NPDCCH is configured according to a DRX cycle and a transmittingtime of the WUS is determined to be prior to the transmission startingtime of each paging NPDCCH by a predetermined offset. When available DRXsizes are {1.28s, 2.56s, 5.12s, 10.245} and 10.24s is selected, theinterval between the WUS and the paging may increase excessively. Toovercome this problem, T may be determined to be as small as possible todetermine offset-long between the WUS and the paging.

The equation of determining t_(offset-long) may also be used when atransmission of signal-A is not applied. For example, regarding thetransmission position of signal-A determined by Equation 5, one or morechannel-B transmissions may correspond to one signal-A transmissionposition according to the value of T and/or X.

(Method 10) Signal-A May Include Information for a Transmission Positionof Corresponding Channel-B.

When UEs having different UE capabilities share one transmissionposition of signal-A as in the method of Method 9, some UEs may detectinformation for unintended (or wrong) channel-B. For example, whensignal-A is the WUS and channel-B is the paging NPDCCH, the WUStransmitted to wake up a UE having the offset-long UE capability mayalso wake up a UE having the offset-short UE capability, which sharesthe same WUS transmitting time, thereby causing unnecessary powerconsumption.

To overcome the above problem, the present disclosure proposes a methodof including information for a transmission position of correspondingchannel-B in signal-A by a base station. For example, this informationmay indicate a UE capability that determines an offset size. Whendetecting information corresponding to its UE capability in signal-A, aUE may monitor corresponding channel-B according to a determined offset.

When signal-A is configured as a sequence in the method of Method 10,information included in signal-A may be identified by a sequence and/ora cover code or scrambling. For example, a Zadoff Chu (ZC) sequence isused as a base sequence for signal-A, a root index, a cyclic shiftvalue, or the like of the ZC sequence may be used, or a cover code or ascrambling code may be applied.

When the method of Method 10 is used, one or more of informationsrepresented by signal-A may be used to indicate two or more UEcapabilities at the same time. This may be intended to simultaneouslyprovide information to a plurality of UEs having different UEcapabilities at one transmitting time of signal-A shared by theplurality of UEs. For example, when two UE capabilities exist, three ormore sequences may be transmitted in one signal-A, two of the sequencesfor distinguishing UEs with the respective UE capabilities and the othersequence for one common indication to UEs with all UE capabilities.

When signal-A including information applied commonly to all UEcapabilities is transmitted as in the above-proposed method, a UE havingthe respective UE capability may apply an offset corresponding to its UEcapability and receive channel-B accordingly. This may be intended toguide transmission and reception of channel-B suitable for a UEcapability and thus allow the UE to obtain information directed to theUE or perform an optimized operation.

Alternatively, when signal-A including information applied commonly toall UE capabilities is transmitted as in the above-proposed method, UEswith all UE capabilities may receive channel-B by applying a maximumoffset. This may be intended to prevent the increase of overhead causedby unnecessary repeated transmissions of channel-B on the part of thenetwork, when channel-B includes common information irrespective of allUE capabilities.

(Method 11) the Number of Transmission Positions of Channel-BCorresponding to Signal-A May be Determined According to an OffsetBetween Signal-A and Channel-B.

When the offset between signal-A and channel-B is longer than anoccurrence periodicity of channel-B, one or more signal-A occurrencetime positions may additionally exist during the offset period betweensignal A and corresponding channel-B. When information for channel-Bthat is carried by signal-A is valid for a predetermined time period,repeated transmissions and monitoring of signal-A may be inefficient interms of network overhead or UE power saving. For example, when signal-Ais the WUS and channel-B is the paging NPDCCH, the base station maytransmit the paging NPDCCH repeatedly in a plurality of POs to enable aUE to receive paging reliably. In this situation, for example, the UEmay simply monitor signal-A continuously before transmission ofcorresponding channel-B starts, after the UE obtains signal-A once.However, the repeated monitoring of the WUS before successful decodingof the paging NPDCCH may lead to continuous decoding of information forthe same purpose and hence unnecessary power consumption.

To overcome the above problem, the present disclosure proposes a methodof determining the number of transmission positions of channel-Bcorresponding to signal-A according to an offset between signal-A andchannel-B. Specifically, the number of transmission positions ofchannel-B corresponding to signal-A may be determined such that theoffset between signal-A and channel-B is determined based on a specificthreshold. For example, the specific threshold may be the periodicity ofchannel-B (or a value proportional to the periodicity of channel-B). Forexample, when signal-A is the WUS and channel-B is the paging NPDCCH,the offset threshold may be the periodicity of a PO (e.g., a DRX cycle).

In a specific example of the proposed method, there are two offsetsbetween signal-A and channel-B: offset-long, that is, an offset largerthan the transmission periodicity of channel-B and offset-short, thatis, an offset shorter than the transmission periodicity of channel-B.The UE may be configured to identify a mapping relationship betweensignal-A and channel-B according to an offset applied to the UE. Forexample, one transmission position of channel-B may be set incorrespondence with signal-A, for a UE with offset-short, and two ormore transmission positions of channel-B may be set in correspondencewith signal-A, for a UE with offset-long.

When a one-to-multi correspondence is built between signal-A andchannel-B in the above proposed method, the number of correspondingchannel-B transmission positions may be (1) predetermined in thestandards, (2) configured by a base station, or (3) determined byanother parameter. When the number of corresponding channel-Btransmission positions is predetermined in the standards, the UE mayadvantageously perform a predetermined operation all the time withoutadditional signaling. Despite the advantage, an inefficientcorrespondence may be generated under circumstances, for example, inview of an offset size. When the number of corresponding channel-Btransmission positions is configured by a base station, the number maybe determined by higher-layer signaling such as an SIB or RRC signaling.In spite of the advantage of a possible efficient configurationaccording to an offset size or an operation scheme of a UE, this methodmay cause additional signaling overhead. When the number ofcorresponding channel-B transmission positions is determined by anotherparameter, the parameter may be, for example, an offset size and/or thetransmission periodicity of channel-B. In an exemplary specific method,the parameter may be the number of all transmission positions ofsignal-A between signal-A and corresponding channel-B. In anotherexample of determining the number of corresponding channel-Btransmission positions by another parameter, the parameter may be aneDRX configuration. In an exemplary specific method, a differentcorrespondence may be established between signal-A and channel-B,depending on whether eDRX is configured.

G.3 Flowcharts According to the Present Disclosure

FIG. 32 is an exemplary flowchart illustrating a method of the presentdisclosure. While the example of FIG. 32 is described in the context ofa terminal (e.g., UE) operation, an operation corresponding to theoperation illustrated in FIG. 32 may be performed by a base station.

Referring to FIG. 32, a UE may determine a time offset between areceiving (or transmitting) time of a specific signal (e.g., signal-A)and a receiving (or transmitting) time of a specific channel (e.g.,channel-B) related to the specific signal (S3202). For example, the UEmay determine the time offset between the receiving (or transmitting)time of the specific signal (e.g., signal-A) and the receiving (ortransmitting) time of the specific channel (e.g., channel-B) related tothe specific signal based on one or a combination of two or more of themethods (e.g., Method 1 to Method 6) described in Section G.1. Thereceiving (or transmitting) time of the specific signal may refer to thereception (or transmission) starting time of the specific signal or thereception (or transmission) ending time of the specific signal.

More specifically, for example, a time offset t_(offset-alpha) may bedetermined based on Method 1 of the present disclosure in S3202. Inanother example, a time offset t_(offset-sum) may be determined based onMethod 2 of the present disclosure in S3202. The time offsett_(offset-sum) may be determined based on a first time offset (e.g.,t_(offset-alpha)) and a second time offset (e.g., t_(offset-beta)).

Independently of or additionally to the afore-described examples, whenthe receiving (or transmitting) time of the specific signal is anunavailable time resource in S3202, the time offset may be postponed toa closest available time resource (or the time offset may be determinedby excluding time resources until the closest available time resource)(e.g., refer to Method 3 of the present disclosure). Alternatively, whenthe receiving (or transmitting) time of the specific signal is anunavailable time resource in S3202, the time offset may be advanced to aclosest available time resource (or the time offset may be determined byincluding time resources until the closest available time resource). Forexample, the unavailable time resource may include a subframe which hasnot been configured as a valid subframe (or an invalid subframe). In amore specific example, the unavailable time resource may include asubframe except for a subframe configured as an NB-IoT DL subframe (or asubframe which has not been configured as an NB-IoT DL subframe) (by thebase station).

Independently of or additionally to the afore-described examples, aminimum gap may be ensured between the reception (or transmission)ending time of the specific signal (e.g., signal-A) and the reception(or transmission) starting time of the specific channel (e.g.,channel-B) (e.g., refer to Method 5 of the present disclosure).

Independently of or additionally to the afore-described examples, thetime offset may be determined only based on transmission resourcesavailable for transmission of the specific signal (e.g., signal-A)(refer to Method 6 of the present disclosure).

The UE may determine a time position at which the specific signal (e.g.,signal-A) is transmitted based on the time offset determined in S3202,and monitor the specific signal (e.g., signal-A) at the determined timeposition. Monitoring may refer to an operation of detecting and/ordecoding a signal.

For example, the time position at which the specific signal (e.g.,signal-A) is received (or transmitted) may be determined based on thetime offset and the receiving (or transmitting) time of the specificchannel (e.g., channel-B). In a more specific example, the received (ortransmitted) time position of the specific signal (e.g., signal-A) maybe determined by applying (e.g., adding) the time offset to thereceiving (or transmitting) time of the specific channel (e.g.,channel-B).

In S3204, upon detection of the specific signal (e.g., signal-A) at thedetermined time position, the UE may monitor the specific channel (e.g.,channel-B) based on the time offset determined in S3202. On thecontrary, when the UE fails to detect the specific signal at thedetermined time position in S3204, the UE may skip monitoring thespecific channel (e.g., channel-B) (or the UE may not monitor thespecific channel (e.g., channel-B).

FIG. 33 is an exemplary flowchart illustrating a method of the presentdisclosure. While the example of FIG. 33 is described in the context ofa terminal (e.g., UE) operation, an operation corresponding to theoperation illustrated in FIG. 33 may be performed by a base station.

Referring to FIG. 33, the UE may receive a plurality of time offsetinformations in S3302. For example, the UE may receive a plurality oftime offset informations including first time offset information (e.g.,offset-short) and second time offset information (e.g., offset-long). Ina more specific example, the first time offset information may beconfigured to have a shorter length than the second time offsetinformation. As described before, time offset information may indicate atime offset between the reception (or transmission) (starting or ending)time of a specific signal (e.g., signal-A) and the reception (ortransmission) (starting or ending) time of a specific channel (e.g.,channel-B) related to the specific signal.

In S3304, the UE may determine a time position for the specific signal(e.g., signal-A) based on one of the plurality of time offsetinformations, and monitor the specific signal at the determined timeposition. Monitoring may refer to an operation of detecting and/ordecoding a signal.

According to the present disclosure, the one time offset information maybe determined based a UE capability of the UE (e.g., refer to Method 8of the present disclosure), and the UE may report the UE capability tothe base station before performing this method. The plurality of timeoffset informations may be received in system information (or an SIB) oran RRC signal. Further, the plurality of time offset informations may bereceived in independent fields of system information (or an SIB) or anRRC signal (e.g., refer to Sub-method 8-1). Further, one or more of theplurality of time offset informations may be values fixed in thestandards (e.g., refer to Sub-method 8-2). Further, the plurality oftime offset informations may be indicated by the same field inhigher-layer signaling such as an SIB or RRC signaling (e.g., refer toSub-method 8-3). Independently or additionally, the time offsetinformation may be determined based on one or more of the methodsdescribed in Section G.1 in combination.

The specific signal (e.g., signal-A) may be a physical signal, and thespecific channel (e.g., channel-B) may be a physical control channel.For example, the specific signal (e.g., signal-A) may be a WUS, and thespecific channel (e.g., channel-B) may be a paging NPDCCH.

Alternatively, instead of the plurality of time offset informations, aplurality of option informations may be configured for the UE, and thebase station may signal information indicating one of the plurality ofoption informations to the UE in S3302 of FIG. 33 (e.g., refer to Method7 of the present disclosure). In this case, the UE may determine a timeoffset based on the indicated option information and monitor thespecific signal at a time position determined based on the determinedtime offset in S3304.

Alternatively, the UE may acquire a plurality of time offsetinformations based on Method 9 of the present disclosure in S3302. Inthis case, one of the plurality of time offset informations may bedetermined according to the UE capability based on Method 9 of thepresent disclosure 9, and the UE may monitor the specific signal at atime position determined based on the determined one time offsetinformation.

Upon detection of the specific signal (e.g., signal-A) at the determinedtime position in S3304, the UE may monitor the specific channel (e.g.,channel-B) based on the one time offset information. On the contrary,when the UE fails to detect the specific signal at the determined timeposition in S3304, the UE may skip monitoring the specific channel(e.g., channel-B) (or the UE may not monitor the specific channel (e.g.,channel-B)).

While the methods of the present disclosure have been described focusingon the relationship between the WUS and the paging NPDCCH, the principleof the present disclosure is not limited to the relationship between theWUS and the paging NPDCCH. Particularly, signal-A refers to a specificsignal or channel used to indicate information for another signal orchannel, as described in the beginning of Section G. Accordingly,signal-A may be replaced with a channel used to indicate information foranother channel in the methods of the present disclosure. For example,signal-A may be a physical channel, and particularly, a physical controlchannel (e.g., PDCCH, MPDCCH, or NPDCCH).

For example, signal-A may be a physical control channel (e.g., PDCCH,MPDCCH, or NPDCCH), indicating whether channel-B is to be received(transmitted or monitored) in the methods of the present disclosure. Inthis example, a time offset between signal-A and channel-B may bedetermined in one or more of the methods of the present disclosure incombination.

Particularly, a time offset between signal-A and channel-B may beindicated by signal-A (e.g., refer to Method 10 of the presentdisclosure). For example, the time offset between signal-A and channel-Bmay be indicated by DCI received on a physical control channelcorresponding to signal-A. More specifically, for example, the timeoffset between signal-A and channel-B may be indicated by a specificfield of the DCI.

When the UE is configured with a plurality of time offset determinationmethods (e.g., refer to Method 7 of the present disclosure), with aplurality of time offset informations (e.g., refer to Method 8 of thepresent disclosure), or with a plurality of reception (or transmission)positions of channel-B corresponding to signal-A (e.g., refer to Method9 of the present disclosure), the base station may indicate one timeoffset determination method, one time offset information, or onereception (or transmission) position to the UE by DCI (or a specificfield in the DCI) transmitted and received on a physical control channelcorresponding to signal-A. Alternatively, the base station may indicateone time offset determination method, one time offset information, orone reception (or transmission) position to the UE based on an ID (e.g.,RNTI) used for the physical control channel corresponding to signal-A.

Further, signal-A may be associated with at least one channel-B.Therefore, signal-A may indicate whether one or more channel-Bs are tobe received (transmitted or monitored). Upon detection of signal-A, theUE may monitor one or more channel-Bs based on a time offset determinedaccording to the present disclosure.

G.4 Device Structures

FIG. 34 illustrates exemplary structures of wireless communicationdevices to which the proposed methods of the present disclosure areapplicable.

Referring to FIG. 34, a wireless communication system may include afirst device 3410 and a second device 3420.

The first device 3410 may be a BS, a network node, a transmission UE, areception UE, a wireless device, a wireless communication device, avehicle, a vehicle having an autonomous traveling function, a connectedcar, an unmanned aerial vehicle (UAV), an artificial intelligence (AI)module, a robot, an augmented reality (AR) device, a virtual reality(VR) device, a mixed reality (MR) device, a hologram device, a publicsafety device, an MTC device, an IoT device, a medical device, a FinTechdevice (or financial device), a security device, a weather/environmentaldevice, a device related to 5G service, or a device related to a 4^(th)industrial revolution field.

The second device 3420 may be a BS, a network node, a transmission UE, areception UE, a wireless device, a wireless communication device, avehicle, a vehicle having an autonomous traveling function, a connectedcar, a UA), an AI module, a robot, an AR device, a VR device, an MRdevice, a hologram device, a public safety device, an MTC device, an IoTdevice, a medical device, a FinTech device (or financial device), asecurity device, a weather/environmental device, a device related to 5Gservice, or a device related to a 4^(th) industrial revolution field.

A UE may include, for example, a cellular phone, a smartphone, a laptopcomputer, a digital broadcasting terminal, a personal digital assistant(PDA), a portable multimedia player (PMP), a navigation system, a slatepersonal computer (PC), an ultrabook, and a wearable device (e.g., asmart watch, smart glasses, or a head-mounted display (HMD)). The HMDmay be, for example, a device type worn on the head. For example, theHMD may be used to implement VR, AR, and MR.

The UAV may be, for example, an unmanned aircraft without a human beingonboard, which flies by a wireless control signal. The VR device mayinclude, for example, a device that renders objects or a background of avirtual world. The AR device may include, for example, a device whichconnects an object or background in a virtual world to an object orbackground in a real world. The MR device may include, for example, adevice which merges an object or background in a virtual world with anobject or background in a real world. The hologram device may include,for example, a device which renders 360-degree stereoscopic images byrecording and reproducing stereoscopic information, relying on lightinterference occurring when two laser beams meet. The public safetydevice includes, for example, an image relay device or image devicewearable on a user's body. The MTC device and the IoT device mayinclude, for example, a device which does not require human interventionor manipulation. For example, the MTC device and the IoT device mayinclude a smart meter, a vending machine, a thermometer, a smart bulb, adoor lock, or various sensors. The medical device may include, forexample, a device used for diagnosis, treatment, relief, curing, orprevention of diseases. For example, the medical device may be a deviceused for the purpose of inspecting, replacing, or modifying a structureor a function. For example, the medical device may be a device used forpregnancy adjustment. For example, the medical device may include adevice for treatment, a surgery device, an (in vitro) diagnosis device,a hearing aid, or a device for a procedure. The security device may be,for example, a device installed to avoid danger and maintain safety. Forexample, the security device may be a camera, a closed-circuittelevision (CCTV), a recorder, or a black box. The FinTech device maybe, for example, a device which may provide a financial service such asmobile payment. For example, the FinTech device may include a paymentdevice or a point of sales (POS) terminal. The weather/environmentaldevice may be, for example, a device which monitors weather/anenvironment.

The first device 3410 may include at least one processor such as aprocessor 3411, at least one memory such as a memory 3412, and at leastone transceiver such as a transceiver 3413. The processor 3411 mayperform the afore-described functions, procedures, and/or methods. Theprocessor 3411 may implement one or more protocols. For example, theprocessor 3411 may implement one or more layers of radio interfaceprotocols. The memory 3412 may be coupled to the processor 3411 andstore various types of information and/or commands. The transceiver 3413may be coupled to the processor 3411 and controlled to transmit andreceive radio signals.

The second device 3420 may include at least one processor such as aprocessor 3421, at least one memory such as a memory 3422, and at leastone transceiver such as a transceiver 3423. The processor 3421 mayperform the afore-described functions, procedures, and/or methods. Theprocessor 3421 may implement one or more protocols. For example, theprocessor 3421 may implement one or more layers of radio interfaceprotocols. The memory 3422 may be coupled to the processor 3421 andstore various types of information and/or commands. The transceiver 3423may be coupled to the processor 3421 and controlled to transmit andreceive radio signals.

The memory 3412 and/or the memory 3422 may be coupled to the processor3411 and/or the processor 3421 inside or outside the processor 3411and/or the processor 3421, and may be coupled to another processor byvarious technologies such as a wired or wireless connection.

The first device 3410 and/or the second device 3420 may include one ormore antennas. For example, an antenna 3414 and/or an antenna 3424 maybe configured to transmit and receive radio signals.

FIG. 35 illustrates exemplary 5G use scenarios.

Referring to FIG. 35, three key requirement areas of 5G include (1)enhanced mobile broadband (eMBB), (2) massive machine type communication(mMTC), and (3) ultra-reliable and low latency communications (URLLC).

Some use cases may require multiple dimensions for optimization, whileothers may focus only on one key performance indicator (KPI). 5Gsupports such diverse use cases in a flexible and reliable way.

eMBB goes far beyond basic mobile Internet access and covers richinteractive work, media and entertainment applications in the cloud orAR. Data is one of the key drivers for 5G and in the 5G era, we may forthe first time see no dedicated voice service. In 5G, voice is expectedto be handled as an application program, simply using data connectivityprovided by a communication system. The main drivers for an increasedtraffic volume are the increase in the size of content and the number ofapplications requiring high data rates. Streaming services (audio andvideo), interactive video, and mobile Internet connectivity willcontinue to be used more broadly as more devices connect to theInternet. Many of these applications require always-on connectivity topush real time information and notifications to users. Cloud storage andapplications are rapidly increasing for mobile communication platforms.This is applicable for both work and entertainment. Cloud storage is oneparticular use case driving the growth of uplink data rates. 5G willalso be used for remote work in the cloud which, when done with tactileinterfaces, requires much lower end-to-end latencies in order tomaintain a good user experience. Entertainment, for example, cloudgaming and video streaming, is another key driver for the increasingneed for mobile broadband capacity. Entertainment will be very essentialon smart phones and tablets everywhere, including high mobilityenvironments such as trains, cars and airplanes. Another use case is ARfor entertainment and information search, which requires very lowlatencies and significant instant data volumes.

One of the most expected 5G use cases is the functionality of activelyconnecting embedded sensors in every field, that is, mMTC. It isexpected that there will be 20.4 billion potential IoT devices by 2020.In industrial IoT, 5G is one of areas that play key roles in enablingsmart city, asset tracking, smart utility, agriculture, and securityinfrastructure.

URLLC includes services which will transform industries withultra-reliable/available, low latency links such as remote control ofcritical infrastructure and self-driving vehicles. The level ofreliability and latency are vital to smart-grid control, industrialautomation, robotics, drone control and coordination, and so on.

Now, multiple use cases included in a triangle in FIG. 35 will bedescribed in detail.

5G may complement fiber-to-the home (FTTH) and cable-based broadband (ordata-over-cable service interface specifications (DOCSIS)) as a means ofproviding streams at data rates of hundreds of megabits per second togiga bits per second. Such a high speed is required for TV broadcasts ator above a resolution of 4K (6K, 8K, and higher) as well as VR and AR.VR and AR applications mostly include immersive sport games. A specialnetwork configuration may be required for a specific applicationprogram. For VR games, for example, game companies may have to integratea core server with an edge network server of a network operator in orderto minimize latency.

The automotive sector is expected to be a very important new driver for5G, with many use cases for mobile communications for vehicles. Forexample, entertainment for passengers requires simultaneous highcapacity and high mobility mobile broadband, because future users willexpect to continue their good quality connection independent of theirlocation and speed. Other use cases for the automotive sector are ARdashboards. These display overlay information on top of what a driver isseeing through the front window, identifying objects in the dark andtelling the driver about the distances and movements of the objects. Inthe future, wireless modules will enable communication between vehiclesthemselves, information exchange between vehicles and supportinginfrastructure and between vehicles and other connected devices (e.g.,those carried by pedestrians). Safety systems may guide drivers onalternative courses of action to allow them to drive more safely andlower the risks of accidents. The next stage will be remote-controlledor self-driving vehicles. These require very reliable, very fastcommunication between different self-driving vehicles and betweenvehicles and infrastructure. In the future, self-driving vehicles willexecute all driving activities, while drivers are focusing on trafficabnormality elusive to the vehicles themselves. The technicalrequirements for self-driving vehicles call for ultra-low latencies andultra-high reliability, increasing traffic safety to levels humanscannot achieve.

Smart cities and smart homes, often referred to as smart society, willbe embedded with dense wireless sensor networks. Distributed networks ofintelligent sensors will identify conditions for cost-efficient andenergy-efficient maintenance of the city or home. A similar setup may bedone for each home, where temperature sensors, window and heatingcontrollers, burglar alarms, and home appliances are all connectedwirelessly. Many of these sensors are typically characterized by lowdata rate, low power, and low cost, but for example, real time highdefinition (HD) video may be required in some types of devices forsurveillance.

The consumption and distribution of energy, including heat or gas, isbecoming highly decentralized, creating the need for automated controlof a very distributed sensor network. A smart grid interconnects suchsensors, using digital information and communications technology togather and act on information. This information may include informationabout the behaviors of suppliers and consumers, allowing the smart gridto improve the efficiency, reliability, economics and sustainability ofthe production and distribution of fuels such as electricity in anautomated fashion. A smart grid may be seen as another sensor networkwith low delays.

The health sector has many applications that may benefit from mobilecommunications. Communications systems enable telemedicine, whichprovides clinical health care at a distance. It helps eliminate distancebarriers and may improve access to medical services that would often notbe consistently available in distant rural communities. It is also usedto save lives in critical care and emergency situations. Wireless sensornetworks based on mobile communication may provide remote monitoring andsensors for parameters such as heart rate and blood pressure.

Wireless and mobile communications are becoming increasingly importantfor industrial applications. Wires are expensive to install andmaintain, and the possibility of replacing cables with reconfigurablewireless links is a tempting opportunity for many industries. However,achieving this requires that the wireless connection works with asimilar delay, reliability and capacity as cables and that itsmanagement is simplified. Low delays and very low error probabilitiesare new requirements that need to be addressed with 5G.

Finally, logistics and freight tracking are important use cases formobile communications that enable the tracking of inventory and packageswherever they are by using location-based information systems. Thelogistics and freight tracking use cases typically require lower datarates but need wide coverage and reliable location information.

The methods described above are combinations of elements and features ofthe present disclosure. The elements or features may be consideredselective unless otherwise mentioned. Each element or feature may bepracticed without being combined with other elements or features.Further, an embodiment of the present disclosure may be constructed bycombining parts of the elements and/or features. Operation ordersdescribed in the methods of the present disclosure may be rearranged.Some constructions of any one method may be included in another methodand may be replaced with corresponding constructions of another method.It is obvious to those skilled in the art that claims that are notexplicitly cited in each other in the appended claims may be presentedin combination as an embodiment of the present disclosure or included asa new claim by a subsequent amendment after the application is filed.

The embodiments of the present disclosure may be implemented by variousmeans, for example, hardware, firmware, software, or a combinationthereof. In a hardware implementation, an embodiment of the presentdisclosure may be implemented by one or more application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSDPs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,microcontrollers, microprocessors, etc.

For example, the present disclosure may be implemented a device orapparatus in the form of a system on chip (SOC). The device or apparatusmay be equipped in the UE or the base station, and may comprise a memoryand a processor. The memory stores instructions or executable codes andis operatively connected to the processor. The processor is coupled tothe memory and may be configured to implement the operations includingthe methods in accordance to the present disclosure when executing theinstructions or executable codes stored in the memory.

In a firmware or software implementation, methods according to thepresent disclosure may be implemented in the form of a module, aprocedure, a function, etc which are configured to perform the functionsor operations as described in the present specification. Software codemay be stored in a computer-readable medium in the form of instructionsand/or data and may be executed by a processor. The computer-readablemedium is located at the interior or exterior of the processor and maytransmit and receive data to and from the processor via various knownmeans.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present disclosurewithout departing from the scope of the invention. Thus, it is intendedthat the present disclosure cover the modifications and variations ofthis invention provided they come within the scope of the appendedclaims and their equivalents.

Although schemes of performing uplink transmissions in the wirelesscommunication system of the present disclosure are described focusing onthe examples applied to the 3GPP LTE/LTE-A system/5G system (New RATsystem), the present disclosure can be applied to various wirelesscommunication systems.

What is claimed is:
 1. A method of receiving a downlink signal by a userequipment, the method comprising: receiving first time offsetinformation and second time offset information from a base station, eachof the first time offset information and the second time offsetinformation indicating a time offset between a receiving time of aspecific signal and a receiving time of a specific channel related tothe specific signal, the first time offset information being configuredto have a shorter length than the second time offset information; andmonitoring the specific signal at a time position determined based onone offset information of the first time offset information and thesecond time offset information, wherein the one offset information isdetermined based on a capability of the user equipment.
 2. The methodaccording to claim 1, wherein the first time offset information and thesecond time offset information are received through a system informationblock (SIB).
 3. The method according to claim 2, wherein the first timeoffset information and the second time offset information are receivedthrough independent fields of the SIB.
 4. The method according to claim1, wherein the first time offset information and the second time offsetinformation are received through a radio resource control (RRC) signal.5. The method according to claim 4, wherein the first time offsetinformation and the second time offset information are received throughindependent fields of the RRC signal.
 6. The method according to claim1, wherein each of the first time offset information and the second timeoffset information indicates a time offset between a reception endingtime of the specific signal and a reception starting time of thespecific channel.
 7. The method according to claim 1, wherein each ofthe first time offset information and the second time offset informationindicates a time offset between a reception starting time of thespecific signal and a reception starting time of the specific channel.8. The method according to claim 6, wherein the time position isdetermined based on a paging occasion (PO) configured for the userequipment and the one time offset information.
 9. The method accordingto claim 7, wherein the time position is determined based on a pagingoccasion (PO) configured for the user equipment and the one time offsetinformation.
 10. The method according to claim 1, further comprisingreporting the capability of the user equipment to the base station. 11.The method according to claim 1, further comprising monitoring thespecific channel based on detection of the specific signal.
 12. Themethod according to claim 1, wherein the specific signal is a physicalsignal, and the specific channel is a physical control channel.
 13. Themethod according to claim 12, wherein the physical signal is a wake upsignal (WUS), and the physical control channel is a narrowband physicaldownlink control channel (NPDCCH) for paging.
 14. A user equipment forreceiving a downlink signal in a wireless communication system, the userequipment comprising: a transceiver; and a processor operativelyconnected to the transceiver, wherein the processor is configured to:control the transceiver to receive first time offset information andsecond time offset information from a base station, and monitor thespecific signal at a time position determined based on one offsetinformation of the first time offset information and the second timeoffset information, wherein each of the first time offset informationand the second time offset information indicates a time offset between areceiving time of a specific signal and a receiving time of a specificchannel related to the specific signal, and the first time offsetinformation is configured to have a shorter length than the second timeoffset information, and wherein the one offset information is determinedbased on a capability of the user equipment.
 15. An apparatus for a userequipment for receiving a downlink signal in a wireless communicationsystem, the apparatus comprising: a memory including executable codes;and a processor operatively connected to the memory, wherein theprocessor is configured to execute the executable codes to implementoperations comprising: receiving first time offset information andsecond time offset information from a base station, and monitoring thespecific signal at a time position determined based on one offsetinformation of the first time offset information and the second timeoffset information, wherein each of the first time offset informationand the second time offset information indicates a time offset between areceiving time of a specific signal and a receiving time of a specificchannel related to the specific signal, and the first time offsetinformation is configured to have a shorter length than the second timeoffset information, and wherein the one offset information is determinedbased on a capability of the user equipment.